hybridfree/eevblog-posts huggingface dataset:
24V Dual CCT LED Strip DC Dimming - Page 1
Forum section: electronics / projects

author: larryqiann
author_rank: Newbie
timestamp: January 20, 2020, 03:30:04 am
content: HiI recently purchased a bunch of this really high CRI LED strip. It runs on 24V and has two colour channels to allow it to be CCT tunable. The 24V are common, and the grounds are separate.The obvious solution to dimming/controlling these is to use a N-channel MOSFET to switch them on and off at a high frequency. However, I do not want the light output to have any flicker, and I'm looking for ways to dim them while maintaining a constant DC voltage with minimal ripple. One way would be to use some DC power supplies that accept sinking current, but that might be difficult to find. Furthermore, the dimming needs to be controlled from a microcontroller or PC, and should ideally have 12-bit dimming support to enable continuous dimming.Would there be any way to design a circuit to achieve this? I was thinking about putting a inductor and then a capacitor before the low side switch on each channel, so that the current stays continuous during the off-cycle by charging the capacitor up, which would be discharged by the MOSFET on cycle. Does this sound like a feasible approach? Is there a proper name for this type of circuit?Thanks!

author: Prehistoricman
author_rank: Regular Contributor
timestamp: January 20, 2020, 04:04:30 am
content: Quote from: larryqiann on January 20, 2020, 03:30:04 amAre you sure the CRI and colour temperature are constant with lower voltages? I recently came across an LED COB that produced much warmer white when underpowered. By using PWM, you are making the LED act as if it's running at full power but not all of the time, so you get the correct colour temperature.If you're only concerned about visible flicker, then just turn up the frequency of the switching.Quote from: larryqiann on January 20, 2020, 03:30:04 amYes, a buck convertor! Almost... what do you mean by "discharged by the MOSFET"?
24VAC to logical high (Hakko FX-888 motion sensor Mod) - Page 1
Forum section: electronics / projects

author: Matt_Heilman
author_rank: Newbie
timestamp: January 10, 2014, 01:39:06 am
content: This is part of a schematic I am working on, for my Hakko-FX888 Motion Sensor mod.This portion is used to detect that the 24vac is on, or was recently.Just curious as to what your thoughts are on it?

author: N2IXK
author_rank: Frequent Contributor
timestamp: January 10, 2014, 01:57:50 am
content: Looks reasonable to me. How long a time constant do you want for the "or was on recently" part? A 1uF smoothing cap might be a bit small...

author: Matt_Heilman
author_rank: Newbie
timestamp: January 10, 2014, 03:29:50 am
content: I put the cap in there to flatten the pulsating DC. I have written a 10 second delay into my code.I originally placed the 1n4004 in the circuit, because I didn't want to damage the Opto LED, since it is only capable of withstanding PIV 5VDC.I am curious how Diodes in series divide PIV.

author: N2IXK
author_rank: Frequent Contributor
timestamp: January 10, 2014, 03:45:52 am
content: I assumed you were expecting the charge in the 1 uF cap to hold the LED on for some particular length of time.If you are concerned about reverse breakdown of the LED, add a 1N4148 across it in reverse parallel.

author: mariush
author_rank: Super Contributor
timestamp: January 10, 2014, 04:43:16 am
content: Wouldn't it be easier to simply solder anACS712orACS714and route the transformer cable through the chip?It is more expensive, but simple..

author: calexanian
author_rank: Super Contributor
timestamp: January 10, 2014, 04:49:18 am
content: Looks good to me. We implement that sort of thing all the time. You may want to add lets say a cap on the input line to filter the sig to the micro.

author: Matt_Heilman
author_rank: Newbie
timestamp: January 12, 2014, 04:53:46 am
content: Thanks for the input.
24VDC-1.5A power supply - Page 1
Forum section: electronics / projects

author: akis
author_rank: Frequent Contributor
timestamp: February 06, 2015, 10:50:48 am
content: On another two thread we discussed typical SMPS units as in laptop adapters, wall plug adapters, and LED supplies. Some of them with earthed mains and some with not. Many of them connecting the negative output to the mains earth, some not. All of them using a blue Y capacitor between secondary and primary of the transformer to suppress EMI. Medical graded units use two blue capacitors in series for more safety. Many of them I have tried and they leak voltages in the outputs, both positive and negative, enough to give me jolts.My portable device is powered by two 24VDC/1.5A supplies. Because this device is used on ones person I cannot power it with one of these SMPS without risking jolts, electrocutions and so on.So I decided to make my own supply using a transformer and no (Chinese) SMPS.The first problem is size and weight. Weight is most important. I used a mains toroidal 80VA, 2x18V. It *just* manages to work and it also gets hot. In order to provide some regulation I used a linear control (P-FET controlled by FET op-amp) and this gets damn hot too. The toroidal runs at 60C inside its box.In addition there are still leaks to the earth, very small, but are there. I suspect this is to do with the capacitive coupling between primary and secondary of the toroidal.1) Should I try to find one of the older type E-shaped transformers? Would they keep the windings apart and thus eliminate any leaks?2) Should I try a DC-DC converter rather than the linear regulator that I use now in order to remove some heat from the box?3) Is it at all possible to design a SMPS that will offer the advantages of low weight and less heat and also match the safety profile of the linear version?
250VAC 16A SSR part suggestion - Page 1
Forum section: electronics / projects

author: ali_asadzadeh
author_rank: Super Contributor
timestamp: April 19, 2020, 12:04:57 pm
content: HiI need to buy 1500 units of a SSR that can be used to replace FINDER 16A 250VAC relays (40.61.9.024.0000) I want to know if you know and suggest a SSR with similar prices and specs to this finder relay, also Do we have reliable Chinese manufacturers?

author: wizard69
author_rank: Super Contributor
timestamp: April 19, 2020, 02:04:54 pm
content: Reliable Chinese manufactures require that you know the ins and outs of doing business in China. I couldn’t suggest one as im simply not familiar with the manufactures there and frankly done have a brand name for you.In any event I’m not one to buy junk hardware if I’m concerned about that much power. I’d get on DigiKey or Newark and buy a brand name I trust. Omron and Watlow, come to mind immediately but there are dozens of suppliers to choose from.

author: ali_asadzadeh
author_rank: Super Contributor
timestamp: April 19, 2020, 03:02:56 pm
content: Thanks, then any brand part number do you suggest?
250W controller for the big JBC C470 soldering tools - Page 1
Forum section: electronics / projects

author: baltersice
author_rank: Regular Contributor
timestamp: January 15, 2017, 11:47:58 am
content: I always wanted a JBC soldering station but could never justify spending that kind of money. Now I have got one of their most powerful irons and have only spent 130 bucks and a few old parts.It was a bit more difficult than the thermistor-based Weller irons for example - but totally doableNeeds an instrumentation amplifier for the thermocouple voltage and a heating-pause to get an undisturbed measurement.

author: ZeTeX
author_rank: Frequent Contributor
timestamp: January 15, 2017, 01:54:11 pm
content: Great video! funny as hell, subscribed after first 10 seconds.I wonder,what if you used weller expensive iron? like the Weller WX1011? are they same topology for controlling the temperature or are they easier for DIY?if most of the expensive high power irons are controlling the temperature at about the same way, You could create kinda universal soldering station, could you?

author: bktemp
author_rank: Super Contributor
timestamp: January 15, 2017, 02:08:41 pm
content: I haven't watched the full video, but on the schematic it looks like you are putting +24V or even a negative voltage when using AC directly into the input of an opampe without any protection when the heater is switched on.

author: digsys
author_rank: Unknown
timestamp: January 15, 2017, 02:23:17 pm
content: Awesome work mate. I'd be quite interested in your progress on this, as we have several of those irons :-) and they are quite expensive, as you say.I'll even whip up a "proper" PCB layout for it :-) Can't subscribe without an account?

author: KD0CAC John
author_rank: Frequent Contributor
timestamp: January 15, 2017, 02:48:37 pm
content: There we go again , more goodies for the tool box , smaller than my Weller 450 gun

author: baltersice
author_rank: Regular Contributor
timestamp: January 15, 2017, 04:45:37 pm
content: Quote from: bktemp on January 15, 2017, 02:08:41 pmYes, indeed, I was concerned with that too!The op-amps aren't directly connected to power ground (blue) though.And at least in the 24VDC approach I haven't seen anything above .5V.In final designs it might be a good idea to put 2 reversed (low leakage) diodes between the op-amp inputs and ground to clamp higher voltages that are not coming from the TC.Quote from: ZeTeX on January 15, 2017, 01:54:11 pmYes, sparkybgs UniSolder would be just that. But those silver Weller "pencils" aren't supported yet I think. At least not without modifications.

author: giovannirat
author_rank: Regular Contributor
timestamp: February 07, 2017, 04:13:53 pm
content: Any news on the progress of this project ?
250W metal halide lamp ballast capacitor - Page 1
Forum section: electronics / projects

author: Sceadwian
author_rank: Unknown
timestamp: September 22, 2017, 01:48:49 am
content: I've got a salvaged ballast cap from a 250W metal halide lamp, wonder what I could repurpose it for. Anyone know the internal construction of these? I'll be picking up two more tomorrow so I may just sacrifice one just for curiosity. Would they be useful at any modest DC voltage for pulse currents? I haven't tried to find a datasheet for it yet but I'm guessing they won't have detailed derating info for DC or pulse currents.

author: David Hess
author_rank: Super Contributor
timestamp: September 22, 2017, 02:57:56 am
content: It is an oil filled metalized plastic film capacitor. The plastic film is probably polypropylene.

author: SeanB
author_rank: Super Contributor
timestamp: September 23, 2017, 12:57:13 pm
content: They are reasonable for pulse operation, just will have a somewhat high ESR ( as part of the design, they are after all a wound coil of film with aluminium coating) and with the internal discharge resistor they will not hold charge for long. Great as power factor4 correction asa they do not shock you on unplugging, and will remove a lot of harmonics off the mains as well.
25KHz Ultrasonic Transmitter - Page 1
Forum section: electronics / projects

author: Sebeom
author_rank: Newbie
timestamp: February 29, 2016, 11:20:51 am
content: Hello,I would like to design the ultrasound transmitter. PZT capacitance is about 2300pF. I want to increase the transmit voltage up to 80Vpp. Is there anyone who has a good schematic for my application? I attached my draft schematic.Thanks, Sebeom

author: Audioguru
author_rank: Super Contributor
timestamp: February 29, 2016, 02:59:44 pm
content: The maximum allowed output current from a 555 is 200mA then its output voltage is about 2.5V less than its positive supply.The base-emitter voltage of a 2N3055 is about 1.1V when its base current is hundreds of mA. Then the 10 ohm resistor limits the current to (12V - 2.5V - 1.1V)/10 ohms= 840mA which will cause the 555 to go up in smoke. How did you calculate such a low value resistor?You need an output of only about 2.3W so why are you going to use this circuit that might try to produce 100W?Will the ultrasonic piezo transducer survive a voltage as high as 80V?

author: Sebeom
author_rank: Newbie
timestamp: March 01, 2016, 01:10:47 am
content: Thanks for your comment!I don't understand the base current calculation of 2N3055. If the output voltage of 555 timer is 2.5V, the base current will be (2.5V-1.1V)/10ohm = 140mA. I selected the low value resistor to increase the collector current of 2N3055.Here is my PZT specification. I understand the input directivity is maximum allowable voltage of PZT.Center Frequency: 25±1.0kHzSPL: ?115dBSensitivity: ?-65dBDirectivity: 60±15°Capacitance: 2300±15%pFInput Directivity: 80Vp-p maxCould you let me know how did you calculate the 2.3W power consumption?

author: Audioguru
author_rank: Super Contributor
timestamp: March 01, 2016, 01:47:15 am
content: I did not say the output voltage of the 555 is only 2.5V. It is 2.5Vless than your 12V supplyso it is about +9.5V. The 2.5V loss is shown on the datasheet of the 555 when its output current is at its maximum allowed 200mA. Then the value of the transistor base resistor is much too low and the resulting very high current will burn out the 555.At 25kHz, the reactance of the 2300pF is 2783 ohms then the power with 80V is (oh, the p-p voltage is 80Vp-p, then the peak voltage is 40V, then the power in the reactance of the piezo is 40V squared/2783 ohms= 0.575W peak and its peak current is 0.575W/40V =14.4mA. Then why BLAST 840mA to the input of the 2N3055?

author: Sebeom
author_rank: Newbie
timestamp: March 01, 2016, 05:24:02 am
content: Hi Audioguru,I understand your explanation about base current calculation. You right I don't need 840mA to the base current but I need to increase the collector current for primary coil of transformer. I would like to use the trasnformer to increase the transmit pulse voltage to the PZT. Do you think transformer is good choice for maximum power transfer to the PZT? If so, I need to impedance match from transformer to PZT for maximum power transfer. Could you calculate the proper turn ratio of transformer and inductor value of primary and secondary coil?Thanks, Sebeom
26650 holder - Page 1
Forum section: electronics / projects

author: akis
author_rank: Frequent Contributor
timestamp: June 22, 2017, 08:42:47 am
content: HelloI am trying to put together a battery pack composed of 6 x 26650s and I have bought plastic holders from ebay, but they take up a lot of space and it is unworkable. If I put 6 x 26650s side by side with small gaps, they take around 16cm. The holder I am looking for should be sturdy enough to hold them in place and also allow regular insertion and removal for recharging or replacing bad cells. Any idea how I could do it?Maybe I can repurpose an old style D size battery charger they usually have sturdy spring loaded contacts.But I would have thought that 26650s are the way forward and that there would be plenty of holders to choose from.

author: ajb
author_rank: Super Contributor
timestamp: June 22, 2017, 11:15:39 am
content: Do you have a PCB or other flat plate you can mount to? You can get C-size two-piece battery clips and mount them at the appropriate distance for your 26650s, something like these:http://www.keyelco.com/category.cfm/Cylindrical-Cell-Clips-THM-and-SMT/For-C-Batteries/p/404/id/943/c_id/953You can also buy the sort of contacts and springs that are meant to be installed into a housing, if you have the ability to fabricate the housing:http://www.keyelco.com/category.cfm/Battery-Coin-Cell-Holders-Contacts-Clips/Cylindrical-Cell-Contacts/p/404/id/410

author: innkeeper
author_rank: Unknown
timestamp: June 23, 2017, 05:25:20 am
content: https://www.digikey.com/en/product-highlight/k/keystone/26650-battery-holders

author: akis
author_rank: Frequent Contributor
timestamp: June 28, 2017, 10:19:02 am
content: Thanks, I now have some more ideas.
27C128 to 2564 Adapter - Page 1
Forum section: electronics / projects

author: Hoffy84
author_rank: Contributor
timestamp: September 10, 2022, 09:34:15 am
content: Hi guys,Arcade game board I’m working on. Without getting into so much detail, there is a mod you can do, to make it switchable between Punch-Out and Super Punch-Out (The sequel), by bank switching various eeproms.My particular board version uses a few 2564 eeproms, and I am trying to adapt 27C128’s to them in this section of the schematic.On the 2564s:>CS1 & CS2 are both grounded, as in the schematic>PD/PGM in the schematic appears to be used as chip select, so seems to be where I want to wire OE (G) to the 27C128 (Pin 22 to Pin 22)>I need to use A13 on the 27C128 to bank-switch.There isn’t really a definitive way to match a 27 to 25 pin for pin, and you have to route it depending on how your board circuitry is laid out. Can you take a look, and see if this will work? I plan on fabbing adapter pcb’s for each eeprom.- Thanks! Jeff
27C512 clock speeds - Page 1
Forum section: electronics / projects

author: Big Ron
author_rank: Newbie
timestamp: June 27, 2013, 01:11:52 pm
content: <delurk>I find a need to update some firmware on a number of boards that have an Atmel AT27C512R-12JC 32PLCC socketed eprom.Can anyone confirm my understanding that I can put a faster chip in? The current -12 is 120ns, and the -70's I can get (AT27C512R-70JU-ND's from digikey) are 70ns.Further, I intend to source the newer firmware from an working unit by dumping the prom from it.Can anyone recommend or otherwise the Seeit FLASHBIOS? It appears to do everything one would wish despite being stupid cheap.I suppose I'd also appreciate a heads-up if I could/should be using a pin-for-pin alternative, but at less than 1UKP a shot, I'm not sure it's worth it.Thanks</delurk>

author: digsys
author_rank: Unknown
timestamp: June 27, 2013, 01:22:30 pm
content: 1/ It would be extremely unusual NOT to be able to use a faster chip, especially parallel devices. I've never seen it to be an issue.Using faster chips was a problem once with drams in motherboards, but that was a pairing / banking issue.2/ Pretty much everything can program those "old" eproms, just check the Vpp !!3/ Again, pretty much anything works in those "old" parallel eprom sockets. It has very easy / tolerant bus timing.

author: Big Ron
author_rank: Newbie
timestamp: June 27, 2013, 01:27:21 pm
content: 1: This is my opinion, and I've never heard of it being an issue.2: I presume that if it's listed as a compatible device for programming in the docs for the programmer, it can choose & generate the right Vpp by reading the ID off the prom.3: My experience is that you can do stupid things with eproms and eeproms (especially blowing bioses etc) but for this application I'd like to be somewhat sure it'll go before committing to doing it.Thanks for the reply

author: Big Ron
author_rank: Newbie
timestamp: March 20, 2014, 01:51:05 pm
content: Just to conclude this in case anyone ever finds it useful.The Seeit programmer needs the DIP to PLCC adapter they sell to read/program the PLCC chips, and works flawlessly for me. The Atmel EPROMS came from digikey without any issue, the faster ones work where the older ones once did.
28V symetrical PSU for LTC2057 base on LM317/LM337 ? - Page 1
Forum section: electronics / projects

author: Overspeed
author_rank: Frequent Contributor
timestamp: June 13, 2025, 02:30:44 pm
content: HelloI plan to built this circuit for trial on ERT ( Electrical Resistivity Tomography ) so measure the voltage on a circuit with a 24V current source by using Wenner setup which is a 4 wires resistance measurement / shunt measurement with soil as resistorQuestion as I plan to supply ( Vs) the LTC2057 with 28V sysmetrical ( 30V on the schematic ) do a simple setup with a LM337 LM317 or LM117 / 137 as I have some is enought regarding voltage quality ( noise , stability ..)The system wil work with 3 batteries in 12V ( lead car batteries )or I need another solution , I usualy use LM78015 /Lm7915 for +/- 15V or Traco module but I have use 28V systemRegardsOS
29V / 10A Boost Converter design - Page 1
Forum section: electronics / projects

author: brumbarchris
author_rank: Regular Contributor
timestamp: February 05, 2016, 07:57:41 am
content: Hi all,As a continuation to this thread:https://www.eevblog.com/forum/projects/12v-to-24v-%28up-to-28-5v%29-step-up-converter/I have decided to design my own converter for a separate application. As usual, I started by putting on paper what I need first, and I came up with the attached requirements document. I am hereby sharing it for review and I am looking forward to your suggestions with regards to what I should add to the requirements, change in them or remove from them in order to be... well, at today's standards, I guess.Regards,Cristian

author: promacjoe
author_rank: Regular Contributor
timestamp: February 05, 2016, 05:20:25 pm
content: Question, What is the normal/Maximum current draw of your motor. And what is the maximum/minimum allowable error current, For the power supply. These are two separate parameters that You need to define as well.

author: brumbarchris
author_rank: Regular Contributor
timestamp: February 05, 2016, 06:44:15 pm
content: The normal operating current for the motor is 5A. However, it can go up significantly under various mechanical conditions, culminating with a 10A value for a stall condition (which I will be able o detect by feedback from the motor, hence the converter must be able to supply even those 10A). So not sure why you say a value lower than the maximum output current is important in this case. What would I do different in the design if those nominal 5A would be say, 7A? Probably nothing. Maybe it would matter if I wanted to rate the converter for a maximum operating time, in order to limit heat build up, but anyway, ATM the intention is to have it capable of continuously driving a motor under load (even in stall condition) with no time limit.As far as the allowable error current for the supply is concerned, that is a different matter and I can understand its importance. However, in practice, this converter will not be supplied directly from battery, but through a high power MOSFET on a different board. As that MOSFET will be driving an output, that output will also need some degree of protection and I am going to implement in that a programmable current limit (as well as a fused output protection). Since the boost converter is set to draw up to 40A under normal operating conditions, I do not see much sense in putting to much protection on its input. Because if a fault occurs and the current remains within 40A that is enough to cause some serious damage, while a current measurement based protection (either fuse based or smarter) will not be activated.Regards,Cristian
2D Magnetic Field Modeling - Page 1
Forum section: electronics / projects

author: dazz1
author_rank: Frequent Contributor
timestamp: November 03, 2018, 04:34:10 am
content: HiI want to make a Magnabend sheet metal bender seen here:http://aaybee.com.au/Magnabend/Building%20Your%20Own%20Magnabend.htmlI want to refine the design by improving the usable magnetic clamping force. To do this I want to use a basic open source (free) 2D magnetic field simulator.I have found some packages with Google but it is not obvious how long the learning curve is. This is a basic 2D problem so only a basic simulator is required.Any recommendations??Dazz

author: ChunkyPastaSauce
author_rank: Unknown
timestamp: November 03, 2018, 05:16:06 am
content: http://www.femm.info/wiki/HomePage

author: Mr. Scram
author_rank: Super Contributor
timestamp: November 03, 2018, 05:22:50 am
content: Quote from: ChunkyPastaSauce on November 03, 2018, 05:16:06 amVery interesting. Thanks!

author: dazz1
author_rank: Frequent Contributor
timestamp: November 03, 2018, 08:54:30 am
content: Quote from: ChunkyPastaSauce on November 03, 2018, 05:16:06 amThis looks like what I am looking for.
2D plot of LED intensity at given distance on flat surface - Page 1
Forum section: electronics / projects

author: 741
author_rank: Frequent Contributor
timestamp: March 30, 2020, 09:30:05 am
content: What is a good way to display the conversion from radiation pattern to illumination at some distance?Variables are flux (W), distance (m)I'd like to arrange multiple LEDs for reasonable eveness of illumination, and also look at effect of distance. I'd only use 1/distance^2, ignoring dispersion.I was thinking of say a colour-coded or graded shading representing flux, then overlapping those patterns in an image editor.Notice the OPPOSITE DEFINITIONS of "angle" between Luminous and Klaran. What is most usual?
2mm pitch connector housings and matching pins - Page 1
Forum section: electronics / projects

author: perdrix
author_rank: Frequent Contributor
timestamp: July 28, 2023, 05:33:36 pm
content: I'm looking for something that should be easy to find: Some 2mm pitch 5-way housings and crimp pins to fit them.I can find housings but finding pins to match when I hit the mfrs' sites all they show me is crimp sockets.Can anyone point me to some that work together from any of Molew, TE or whoever else.ThanksDavid

author: Gribo
author_rank: Frequent Contributor
timestamp: July 28, 2023, 05:50:40 pm
content: JST:https://www.digikey.ca/en/products/detail/jst-sales-america-inc/SPAL-002T-P0-5/760035Housing:https://www.digikey.ca/en/products/detail/jst-sales-america-inc/PALR-05VF/760039?s=N4IgTCBcDaIAoEEAyAlAtABgKwDUBiIAugL5A

author: perdrix
author_rank: Frequent Contributor
timestamp: July 29, 2023, 08:12:00 am
content: What I was think of was something like the 0.1" Molex 70066 crimp housings and 16-02-0107 crimp pins but in 2mm pitch

author: Infraviolet
author_rank: Super Contributor
timestamp: July 29, 2023, 03:13:53 pm
content: Molex MicroClasp has a 2mm pitch, not sure if you'd be able in practice to crimp its contacts with ordinary tools though (Molex tries to sell insanely expensive crimping tools for each connector type). It comes with premade cable assemblies too.

author: perdrix
author_rank: Frequent Contributor
timestamp: July 30, 2023, 02:10:39 am
content: In the end I couldn't find any with crimp pins so I just ordered these TE Connectivity parts2mm pitch 5-way crimp housings 2316102-5Crimp receptacles for above 5-2316113-6and I'll just use a long pin 2mm header to convert it into a plug.David

author: themadhippy
author_rank: Super Contributor
timestamp: July 30, 2023, 02:20:39 am
content: Quotebit late to the party buthttps://www.toby.co.uk/cable-wire-to-board/200mm-crimp-and-poke/t1m82-samtec-2mm-tiger-eye-crimp-terminal-loose-or-reel/T1M82-L-2426-01-L/might be usefull for the future

author: perdrix
author_rank: Frequent Contributor
timestamp: August 01, 2023, 11:03:59 am
content: Thanks, They might fit standard 2mm housingsD.
2mTD: lab31 6000 mAh power bank - Page 1
Forum section: electronics / projects

author: jitter
author_rank: Frequent Contributor
timestamp: June 04, 2016, 09:59:56 am
content: A 2mTD (2 minute teardown):Sold as a "lab31" LB-PB600WR 6000 mAh power bank, some googling turns up the real manufacturer and type as theExmight XN-091("with it, You have power to fly").It has two outputs: 5 V/1 A and 2 A. The manufacturer recommends to charge it off a 1 A adapter, but on a 2 A adapter it will take around 1.5-1.7 A max. This speeds up charging, probably at the cost of the number of charge cycles the cells will give you.Output of the 1 A port when loaded at 1 A is a nice round 5 V with a quite reasonable 80-90 mVpp~250 kHz ripple. The 2 A port @ 2 A does only slightly less well at 4.9 V and slightly more ripple but not bad at all.Capacity? Well, prior to the teardown I charged my phone (itself with a 2500 mAh battery) a couple of times from around 40-50% which it almost managed 3 times. I don't think it's particularly efficient, but then you would not use this when mains is available anyway. I bought it for the holidays.I will do some tests with my electronic DC load some time soon.A few prods with a small screwdriver opens the case which seems to be ultrasonically welded in only a few spots. The batteries are not pretending to be some A brand, googling HZNB findsHubei Zhongnengas the manufacturer. The orange sleeve goes with the 2000 mAh version. I have no idea about the quality of these cells. They are sitting on ridges in the housing helped by some foam-like sticky tape.It seems to have the requisite protection against the usual mishaps. There is aDW01A"one cell" protection IC, which seems a bit odd when you consider this power bank has three 2000 mAh 18650 cells. But as they're connected in parallel, I guess you could consider it a single 6000 mAh cell. Then there are someFS8205AMOSFETs andPT4606complementary MOSFET (probably, I couldn't find the PT4606 datasheet so took the AO4606 instead). There's also an unmarked (not rubbed off) IC which I presume is a controller.When loading the power bank with 2 A, the big inductor and adjacent FET get too hot to touch (ca. 90 degrees C according to an IR temp sensor). At that output current, the current drawn from the battery is approx. 3.2 A @ 3.7 V => 11.84 W, around 85% efficient.
2N1264 replacement? - Page 1
Forum section: electronics / projects

author: ledtester
author_rank: Super Contributor
timestamp: February 15, 2016, 08:19:00 pm
content: I'm trying to get the following grid dip meter circuit to work. it calls for a 2N1264 germanium PNP transistor. Is there a modern jelly-bean component I can use instead?I've tried using a 2N3906 - it simulates okay, but I can't get it to work on the breadboard.See the second attachment for a description of the component values.Thanks!

author: uncle_bob
author_rank: Unknown
timestamp: February 15, 2016, 08:27:03 pm
content: HiMost of what you attached does not open on my machine. If this is already in there, sorry for the questions:What is the upper frequency limit on the instrument?How badly do you want to retain the existing scale markings?====The 3906 is essentially an audio transistor that happens to work somewhat at RF. From the same era a 2N918 would be a more common part for RF use. Like the 3906, it's silicon rather than germanium. The biasing will not quite be the same.Bob

author: IconicPCB
author_rank: Super Contributor
timestamp: February 15, 2016, 08:42:48 pm
content: search reports nte100 a germanium replacement.

author: ledtester
author_rank: Super Contributor
timestamp: February 15, 2016, 09:44:33 pm
content: Quote from: uncle_bob on February 15, 2016, 08:27:03 pmHi Bob,I'm just trying to use the circuit as a general LC tank oscillator for typical AM radio frequencies.I found it in this book (PDF):http://n4trb.com/AmateurRadio/SemiconductorHistory/Transistor_Circuit_Handbook_for_the_Hobbyist.pdfIt's the 5th project - page 14 in the book, page 20 in the PDF.

author: uncle_bob
author_rank: Unknown
timestamp: February 15, 2016, 10:14:55 pm
content: Quote from: ledtester on February 15, 2016, 09:44:33 pmHiSo the real objective is to make a VFO?There are a *lot* of articles on oscillator design. I would dig in a bit deeper and find one that dates more to the 80's than to the 60's. Grid dipper are designed to be an oscillator that "just barely works". That is what makes them useful. That's generally not what you are after in a more general sense.The magic search terms are:ColpitsVackarSeilerAny of those with or without VFO attached will give you a multitude of hits.Bob

author: Seekonk
author_rank: Super Contributor
timestamp: February 15, 2016, 11:19:48 pm
content: For your silicon replacement I would set R4 to mid position. Add a pot in series with R1. Make the pot 2.5 X value of R1. Adjust pot till it oscillates.
2n222a 2n2907a amp in CAN-3 case in a  HP 8903 - Page 1
Forum section: electronics / projects

author: cncjerry
author_rank: Unknown
timestamp: January 30, 2020, 08:02:36 am
content: Dumb question. I brought the smoke out if my new HP8903a with the processor upgrade. I was probing, found the blown output fuses, replaced them, pulling the leads off, my Parkinsons tremor caused an issue on the output attenuator board. Smoke, etc. I guess the ground lead touched a metal transistor can or something and that was all she wrote. One transistor had a CE short and two 16.2ohm resistors went up in smoke. No other damage from what I can tell. The circuit is signal-carrying. If anyone is interested and has the schematic, they were A6q6,a6q8 and the two, 16.2ohm, current limiting resistors.So here`s the question, should I use a CAN-3 package for both transistors, as they were, or is it safe to switch to plastic? I'm concerned about noise. I have many (read that as 1000s) of the plastic. The cases weren`t grounded, no heat sinks or heat spreaders, etc. This isn`t rf, just the last stage of a high quality, or higher quality, audio oscillator.Thanks,Jerry.T.Hancock

author: moffy
author_rank: Super Contributor
timestamp: January 30, 2020, 11:24:41 am
content: Plastic should be fine: Air Temp: TO18 Pwr@25C = 500mw, TO92 Pwr@25C = 625 mw. Just make sure the pinouts match when you solder the new devices in.

author: macboy
author_rank: Super Contributor
timestamp: January 30, 2020, 02:51:11 pm
content: I agree, there is no harm in trying the plastic. If you desolder safely (clip the body off of the leads and remove leads one-by-one) then you have little risk of damaging the board so you can rework it later to install the metal can parts if necessary. Any extra noise caused by the cheaper parts should be evident when you do a loopback test of the instrument after repair. You are probably familiar with what the THD+N floor was before, so you can compare.

author: cncjerry
author_rank: Unknown
timestamp: January 30, 2020, 04:39:30 pm
content: The plastic parts would allow me to match the gain better. I have a tracer for small signal devices to +/-15v. The manual doesn't say they have to be matched but I will anyway.I clipped the leads and pulled them out like you suggested. I tried the solder sucker on those pins but I've had problem getting that old HP solder to flow with my power gun.I ran the loopback test before I blew it up and it was .0018 for THD but I didn't get the other measurements.Thanks,Jerry
2N7000 & BSS84 gate overvoltage protect. Need ideas! :) - Page 1
Forum section: electronics / projects

author: Rostislav
author_rank: Contributor
timestamp: October 23, 2015, 11:42:49 am
content: Hi, all!In my project i used this circuit (only part. please, see image "Circuit 1.png").Transistors Q1..Q4 working in Zener diode mode (Ustb ~ 10V, Cbe ~ 5pF).This is variant do working normal, if Ugs from M1 & M3 < xx.If Ugs from M1 & M3 > xx, then i have distortion on output the my amplifier. The reason in revers current Ibe Q1..Q2. Transistors M2 & M4 workingnormal(maybe treshold voltage (Ugs) BSS84 < treshold voltage (Ugs) 2N7000).My question for you: what other protect variants can i use? Or maybe protect not need?Need protect with low capacity and low leakage current (divider resistors R5, R3, etc. very big).Very thanks all!!!
2oz to 1oz Cu reduction, what to worry about? - Page 1
Forum section: electronics / projects

author: ANTALIFE
author_rank: Frequent Contributor
timestamp: February 01, 2022, 06:34:37 am
content: Hi AllI have been asked to see if I can reduce the copper thickness on a bunch of boards from 2oz to 1oz. Most of these boards are LED drivers while others have a few impedance controlled tracksSo my question is, what sort of things should I be worried about when reducing the Cu thickness? So far my checklist is:Check heat-sinking capability is adequateCheck trace width is adequate for specified currentCheck track impedance is within tolerance

author: Siwastaja
author_rank: Super Contributor
timestamp: February 01, 2022, 07:35:22 am
content: Thermal simulation is difficult, by far it's easiest to just order prototypes, test in worst-case ambient temperature and monitor board and component temperatures.
2P 18650 UPS module with load sharing - multiple parallel parts - Page 1
Forum section: electronics / projects

author: Peabody
author_rank: Super Contributor
timestamp: January 11, 2024, 06:36:28 pm
content: I previously posted about the single-cell version of this module:https://www.eevblog.com/forum/projects/18650-chargerboost-module-with-load-sharing/msg5041060/#msg5041060I finally got around to ordering the 2P version. Its schematic is shown at the bottom.https://www.ebay.com/itm/186079016381So like the 1S version, there is no output connector, such as a Type-A USB socket. You have to solder wires. But unlike the 1S version, this one has no provision for installing an on/off switch ahead of the boost converter. So short of cutting traces, the only way to turn it completely off is to remove the batteries, which you don't want to do. And while I'm thinking of it, since these cells are in parallel, you want to use unprotected cells for sure so there is never a voltage differential between the cells. However, despite its shortcomings, this module is functional as a UPS and power supply for electronics projects - there is no minimum current shutoff, and you can power the load and charge the battery independently at the same time. It is not a power bank.But what I want to ask about is the use of multiple parts in parallel in this circuit where normally one part would be used. There are two schottky diodes in the load sharing circuit, four (yes 4) P-channel mosfets there as well, two 220uF output capacitors, and two battery protection chips. I assume this is all related to the 3-amp spec for this board, vs 1A for the 1S board. But even so, I wonder what these multiple parallel parts actually accomplish. Also, they didn't double up the schottky diode in the boost circuit. Why not?The datasheets for these parts suggest that only one would be needed for three amps. So what is the point of doubling, or quadrupling, up? I guess I can kinda see the double diodes in a boost circuit, but the diodes are rated 5A, so one should be enough. But maybe not if it gets hot. But why four mosfets? And the overcurrent spec for the protection chip is 9A - why would you need, or even want, two?
2S 18650 charge/balance/overdischarge pcb required which supports a Vin of 10.8V - Page 1
Forum section: electronics / projects

author: aqibi2000
author_rank: Regular Contributor
timestamp: September 12, 2020, 01:38:36 pm
content: I have a vin of 10.8V from a circuit to go into an off the shelf board I can buy off eBay/amazon for a 2S 18650 battery (max draw is around 1a)Can I please get some assistance

author: jmibk
author_rank: Regular Contributor
timestamp: September 12, 2020, 02:52:11 pm
content: Maybe the LM2679 step down converter might be a solution. Datasheet:https://www.ti.com/lit/ds/symlink/lm2679.pdf?HQS=TI-null-null-alldatasheets-df-pf-SEP-wweHere you can set a current limit of 1A (your choice), that gives you the characteristic CC-CV charging curve (but with no shutdown after full charge).

author: tunk
author_rank: Super Contributor
timestamp: September 12, 2020, 03:18:35 pm
content: The TP5100 might do it.

author: aqibi2000
author_rank: Regular Contributor
timestamp: September 12, 2020, 11:21:23 pm
content: Hi thanks for the repliesJust to clarify I’m not after a buck converter I need a 2 cell balance board which accepts an input voltage of 10.8vLike the ones in my picture

author: NiHaoMike
author_rank: Super Contributor
timestamp: September 13, 2020, 12:03:41 am
content: What you want is a 2S BMS with built in charge controller, which I don't think exists as an off the shelf module.
2S Li-ion charger - Page 1
Forum section: electronics / projects

author: LukeW
author_rank: Frequent Contributor
timestamp: September 01, 2017, 12:10:21 pm
content: Any suggestions as to what chip(s) I might use for a 2S Li-ion charger?- 2x series lithium-ion or lithium polymer.- 9VDC wall wart for charging. User plugs in 9VDC supply, easy charger UX.- No buillt-in protection in 18650 cells, overcharge protection, over discharge prorection, balancing etc is all provided externally to keep the cells happy.- Output rail at ~7.2V or so, whatever the battery voltage is, to the downstream loads.- 4x LEDs "fuel gauge".- Minimal quiescent power draw in the protection circuit or fuel gauge.- About 2Ah at least, 3Ah desirable.I'm thinking 2x discrete 18650s inside the device, but I'm open to considering alternatives (an off-the-shelf 2S LiPo, if that might be easier, or an off-the-shelf pack with protection electronics already.)Being able to replace the cells in a few years if they crap out without replacing the whole device would be nice.
2SC1815 vs SS9014 noise  - Page 1
Forum section: electronics / projects

author: Deactivated-1
author_rank: Frequent Contributor
timestamp: November 03, 2023, 06:06:07 pm
content: https://media.digikey.com/pdf/Data%20Sheets/Toshiba%20PDFs/2SC1815.pdfhttps://www.onsemi.com/pdf/datasheet/ss9014-d.pdfThey show no noise charts. Some datasheets claim a 1db typical noise rating for the 2SC1815, others - 0.2db.While the SS9014 shows 0.9db typical.Does anyone have any experience with these transistors? which one has less noise in the ~5-10k impedance range?Or does anyone have a noise chart for them?

author: magic
author_rank: Super Contributor
timestamp: November 04, 2023, 09:09:17 am
content: 1. You seem to be worrying about less than 1dB difference, at least at 1kHz.2. It's high impedance, so the one with higher β should win, except at low frequencies where dragons are.3. Run them at the lowest current you can get away with; the 0.1mA in the datasheet is likely still not their noise optimum.

author: David Hess
author_rank: Super Contributor
timestamp: November 04, 2023, 04:51:54 pm
content: Quote from: magic on November 04, 2023, 09:09:17 amThe source impedance combines with the ratio of voltage to current noise to produce a lowest noise as a specific collector current. The limitation here is that transconductance varies with collector current also so there may be a lower or higher limit.Basically the collector current can be tuned for lowest noise for a given source impedance. High beta transistors usually give specifications at lower collector currents, like 100 microamps, but optimum for lowest noise still depends on the source impedance.
2Way audio amplifier project - Page 1
Forum section: electronics / projects

author: strawberry
author_rank: Super Contributor
timestamp: June 09, 2017, 06:14:48 pm
content: 2Way audio amplifier project

author: Benta
author_rank: Super Contributor
timestamp: June 09, 2017, 06:46:46 pm
content: Nice pics... I hope you'll tell us more at some point.

author: strawberry
author_rank: Super Contributor
timestamp: June 25, 2017, 08:15:42 pm
content: Concerned about feedback resistors 100k + 8.2k values. Is this feedback dc blocking capacitor C3, C5 necessary at first place?

author: edavid
author_rank: Super Contributor
timestamp: June 25, 2017, 09:09:46 pm
content: Quote from: strawberry on June 25, 2017, 08:15:42 pmLM3886 input offset voltage spec is 10mV max, so it depends on how you feel about DC on your output.P.S. Those backward facing regulators are confusing.
2wire sensing 10level water level <5$ - Page 1
Forum section: electronics / projects

author: dave_j_fan
author_rank: Regular Contributor
timestamp: August 14, 2016, 05:04:18 pm
content: A discrete version..i like BJTsin reality i will add a fet touch timer ...so this unit will display for say 5minsand save battery for yearsadd some more BJts and calibrate u can go 10 or more levels

author: StillTrying
author_rank: Super Contributor
timestamp: August 16, 2016, 02:46:37 pm
content: In theory you could use a CMOS hex buffer or 2.
2x40 LCD but graphic? - Page 1
Forum section: electronics / projects

author: MT
author_rank: Super Contributor
timestamp: October 08, 2018, 07:50:26 pm
content: 2X40 character LCD is quite industry standard but are there any interface and size equivalent graphic's around?or one of same length but slightly wider, max 37-41mm wide? The closest is the industry standard 64x256 pixel.Like:https://www.buydisplay.com/default/3-8-inch-graphic-lcd-256x64-cog-display-module-uc1698-white-on-blueAnyone bought something from them, experience?

author: SiliconWizard
author_rank: Super Contributor
timestamp: October 08, 2018, 07:56:45 pm
content: There are plenty.You can take a look here to get an idea:https://www.crystalfontz.com/https://www.newhavendisplay.com/

author: MT
author_rank: Super Contributor
timestamp: October 08, 2018, 08:10:34 pm
content: Thanks for the tip's SiliconWizard...https://www.crystalfontz.com/product/cfag20232ctmitt-202x32-graphic-lcdIs on the path but the problem or advantage with 2x40 is its 180mm length, sort of.
3.0V regulator? - Page 1
Forum section: electronics / projects

author: technix
author_rank: Super Contributor
timestamp: May 25, 2017, 04:17:07 pm
content: I am going to ditch the AXP203 PMIC for Allwinner V3s in my DIY camera design and opt for a few SOT23-5 regulators and a STM32F030F4P6 as the platform controller IC. The AXP203 is a nightmare to wire up and I am not comfortable soldering QFN with an iron. Now I am trying to find the LP2980-3.0 for the 3.0V VDDANA rail (2.8-3.3V limits, 3.0V typical). However so far, no luck. Nobody I know of is selling those. Is there any alternative solutions?How to generate the 3.0V rail without the LP2980-3.0 then? On the board there are LM3671-3.3 switch-mode regulators already there for the I/O rails, can I drop it with a SS14 Schottky rectifier or BAT54A dual Schottly diode, put a LC filter after that and call it a day?

author: Andreas
author_rank: Super Contributor
timestamp: May 25, 2017, 04:31:12 pm
content: https://www.digikey.de/product-detail/de/texas-instruments/LP2980IM5-3.0-NOPB/LP2980IM5-3.0-NOPBCT-ND/364527?WT.z_cid=ref_findchips_standard

author: JPortici
author_rank: Super Contributor
timestamp: May 25, 2017, 04:57:18 pm
content: or a mic550x?

author: james_s
author_rank: Super Contributor
timestamp: May 25, 2017, 05:00:42 pm
content: You could use an adjustable regulator and calculate the resistor values for 3.0V, it only takes two resistors and you have a fixed regulator of whatever voltage you want.
3.3V & 5V from24VDC - multiple solutions. Is one better than the others? - Page 1
Forum section: electronics / projects

author: MrLikerBiker
author_rank: Newbie
timestamp: January 16, 2014, 11:50:35 am
content: Hello, I have a project that needs 3.3V & 5V DC on board from a 24V DC power supply. I can think of a number of solutions:1. Separate switch mode PSUs for 5V & 3.3V using LM22676MRE-5.0 & LM22675MRE-ADJ2. Single switch mode PSU to get from 24VDC to, say, 6VDC and then use 5V & 3.3V linear regulators (LR) connected to the 6V.3. Single switch mode PSU to get from 24VDC to, say, 6VDC an then use a 5V LR connected to 6V and a 3.3V LR connected to the 5VThings that I am trying to juggle are:a. board space.b. noise.c. efficiency (heat generated in wasted power)d. design simplicity.Opinions?

author: Psi
author_rank: Super Contributor
timestamp: January 16, 2014, 11:57:48 am
content: We really need to know the 3.3 and 5V current required before we can recommend options

author: tszaboo
author_rank: Super Contributor
timestamp: January 16, 2014, 12:22:18 pm
content: Quote from: Psi on January 16, 2014, 11:57:48 amAlso, what is analog, what is digital, what frequency you want to run your SMPS, what is the end application, how much % noise, how many layers, how many devices are connected to each rail, and how they are distributed... Power designs are not simple.

author: MrLikerBiker
author_rank: Newbie
timestamp: January 16, 2014, 04:52:57 pm
content: 5V needs to supply about 1.2A3V3 needs to supply about 0.4AEach supply has a mixture of analog and digital componentsThe board is 4 layer boardSwitching frequency is 500KHz

author: Rufus
author_rank: Super Contributor
timestamp: January 16, 2014, 05:26:44 pm
content: Quote from: MrLikerBiker on January 16, 2014, 04:52:57 pmThen probably switch mode 24 to 5v and LDO regulate 5 to 3.3.The 3.3v supply is 1.3W. A 5 to 3.3v linear regulator efficiency is 66% is it worth another switcher to improve that?

author: MarkL
author_rank: Unknown
timestamp: January 16, 2014, 07:09:15 pm
content: If "simple" is high on your list, complete switcher modules are in the same price range as your proposed LM22676MRE approach. For example, Murata offers the OKI-78SR series which has 5V and 3.3V at 1.5A for around US$4 (plus a possible input decoupling cap). The form factor is a 78xx TO-220 replacement.For that price you could do one of each 5V and 3.3V, but I would probably do linear for the 3.3V off the 5V as Rufus suggests. It would be less noisy and probably a little bit cheaper (would dissipate 0.7W @ 0.4A).

author: kripton2035
author_rank: Super Contributor
timestamp: January 16, 2014, 07:45:37 pm
content: there are also double switching regulators by texas instrument or maxim.