hybridfree/eevblog-posts huggingface dataset:
12V Inverter for portable Cossor CDU150 Oscilloscope Design? - Page 1
Forum section: electronics / projects

author: Chris56000
author_rank: Frequent Contributor
timestamp: May 20, 2020, 08:43:11 am
content: Hi!Having donated the mains transformer from a Cossor CDU150 35MHz portable oscilloscope to a Vintage Radio Forum Member, I'm thinking of using it as a test bed for a 12V battery conversion.The power supplies required are:–a) +20V at 1A;b) +150V at 300mA;c) +67V at 300mA;d) –67V at 300mA;The voltage rails quoted above assume the retention of the original power supply stabilization circuits fed off the original 50Hz transformer, now removed.The power consumption given in the handbook (I have an original ring bound one coming!) is 110VA.The e.h.t. and p.d.a. comes from it's own inverter circuit which will be retained, and the highly insulated CRT heater supply would be obtained from an isolated dc–dc converter operated from the incoming 12V battery supply.What size transformer kit would best power this, using a TL494 or SG3524 based flyback design, and where can I obtain easy–to–understand transformer winding data?It's not necessary for output rectifiers and capacitors to be provided on the new inverter pcb., four isolated a.c. outputs plus the CRT heater from a DC–DC module is all that's needed!Are there any companies that would manufacture/wind a suitable transformer for me at an economic price I can approach?Chris Williams
12v Lithium battery USB-charge/PSU/battery protection module - Page 1
Forum section: electronics / projects

author: sparksflying
author_rank: Contributor
timestamp: October 03, 2022, 02:57:00 am
content: Hello,I was just watching the latest video from GreatScott! on youtubeHas anyone come across a module that has the following features (or close to):- Attaches to a 11.1v (3S) Lipo/LiIon battery (Could also use 3.7V battery and boost to 12v)- Charges battery via 5V USB (and balance charges)- Supplies 11.1V output (higher current output better, but 2-3A is fine)- Has battery undervoltage protection cutoffI had a look on Aliexpress, but didn't find anything suitable.Thanks
12V lithium pack + charging - Page 1
Forum section: electronics / projects

author: wavey
author_rank: Newbie
timestamp: November 25, 2015, 08:00:36 am
content: Hi everyone,I'm building a lithium battery powered device driving a bunch of 12V motors at around max 3A, but now wondering if I made the right choices. In my view there are two options:1. Parallel cells:Each cell gets a separate battery charger ICa boost converter. Correct voltages are easily handled by standard lithium charger ICsBoost converter to go to 12V for motors5V power supply2. Serial cells3 cells in serial. 12.6V for charging and 11.1V when dischargingBuck converter from power supply to 12.6V with current limit to protect charging.>13V power supplySo far I went with option 2, but I noticed that I'm not that good at making a reliable buck converter, some of them fail to supply enough current. Also the feedback voltage divider needs 0.1% resistors to have enough accuracy and those can be expensive/harder to source. Should I have gone with 1 instead?For reference this is what my current buck converter schematic looks like

author: wavey
author_rank: Newbie
timestamp: November 26, 2015, 06:49:06 am
content: Thanks, I guess you're right. I was a bit too optimistic with rolling my own. I haven't found any 3S IC's but there are plenty of 12V lithium packs on taobao that have charger ICs on them. And I'm never going to make anything cheaper than that..

author: KL27x
author_rank: Super Contributor
timestamp: November 26, 2015, 08:36:45 am
content: QuoteWhat's enough current? This is your maximum charging rate, yeah?It shouldn't be too difficult to get an amp or so out of a buck converter. If you're not good at making your own, maybe just buy an IC and follow the datasheet? Even a linear regulator could work fine, if your Vin isn't too high.

author: KL27x
author_rank: Super Contributor
timestamp: November 26, 2015, 08:46:14 pm
content: QuoteMaybe?I like the mental image of 3 cells in cereal.

author: wavey
author_rank: Newbie
timestamp: November 27, 2015, 06:17:43 am
content: Yeah KL27x got it right. Indeed my buck regulator needs to supply at max charging rate. Some work fine, some only work after I touch them. I guess that suggest some dodgy oscillator that does not start properly. But no clue yet how to fix it.I just have to accept that all the time I spent so far is wasted and should just buy complete 3 cell batteries.
12V Low Battery Discharge Cutoff Circuit  - Page 1
Forum section: electronics / projects

author: sweekly
author_rank: Newbie
timestamp: June 18, 2014, 01:42:50 pm
content: Hey guys, I'm working on a project that I'm stuck on. I need to design a circuit that will shut off a 12v lead-acid battery when it reaches 11v. It also needs to have a hysteresis. The load present on the battery is pretty high at up to 8 amps. I've spent some time looking around, but can't find a good circuit to use and am a little stuck on designing one. If you guys could help point me in the right direction that would be great. Thanks.

author: NiHaoMike
author_rank: Super Contributor
timestamp: June 18, 2014, 02:18:20 pm
content: Add a time delay of a few seconds so that transients do not false trigger it.

author: briandorey
author_rank: Regular Contributor
timestamp: June 18, 2014, 02:31:33 pm
content: I made the same circuit using a MAX8212 chip. The circuit I used can be downloaded fromhttp://briandorey.com/docs/low-voltage-cutoff/LowVoltageCutoff.pdfand the project photos and pcb files onhttp://briandorey.com/post/Low-Voltage-Cut-off-using-MAX8212.aspx

author: richard.cs
author_rank: Super Contributor
timestamp: June 18, 2014, 02:42:32 pm
content: The last one of these I made mechanically latched using the mechanism from a modified MCB. It then held off at zero current consumption (the power the the monitor circuit was also disconnected) until manually reset. In hindsight an RCD would have been far easier to modify.

author: sweekly
author_rank: Newbie
timestamp: June 18, 2014, 03:03:35 pm
content: Thanks to those who have responded so far, I guess I should have mentioned that I don't want a mechanical button, or a timer circuit.

author: MLXXXp
author_rank: Frequent Contributor
timestamp: June 18, 2014, 04:15:47 pm
content: If a low side switch is acceptable, here's one I designed for 12V gel batteries, using a LM393 dual comparator and a zener reference. The pots adjust the cutout and re-enable voltages, though they interact with each other.If desired, you could replace the pots with fixed resistors if you determine the proper values for your voltage points. I used pots (20 turn) because I was lazy and wasn't sure what I wanted the switching points to be.The voltage tolerance of Z1 is one of the biggest factors affecting the accuracy of the switching points.Z2 protects Q1 against exceeding the maximum VGSof 20V, since I wanted to be able to handle voltages up to about 30V under some circumstances. You may be able to leave it out.C1 makes sure the circuit switches on when the battery is attached, if the battery voltage is in the hysteresis zone.

author: Mr Smiley
author_rank: Frequent Contributor
timestamp: June 18, 2014, 08:36:42 pm
content: Try this onehttp://danyk.cz/p_ochr_en.html
12V piezo mister capacitive touch work around - Page 1
Forum section: electronics / projects

author: phaseform
author_rank: Regular Contributor
timestamp: November 30, 2018, 10:52:39 am
content: I have a 12v car mister which is operated by a capacitive touch switch. I want to over ride this so it runs when powered always.I haven't worked out the schematic to achieve this.. yet.I'd much rather reverse engineer it and bodge a solution than try control it with a micro-controller...Power cycle is:1. power on: Red LED2. blue LED, mister on3. Blue/red LED, mister low power

author: phaseform
author_rank: Regular Contributor
timestamp: November 30, 2018, 11:29:07 am
content: looks like a little square of aluminium foil can trigger the sensor when grounded, so I'll use a micro controller to trigger it once powered.
+-12V Rails from +24V for Headphone Amp? - Page 1
Forum section: electronics / projects

author: Obsidianxenon
author_rank: Contributor
timestamp: July 25, 2025, 11:33:18 pm
content: I have been building a headphone amplifier recently and was just wondering if I could get away with using a voltage divider from a 24VDC supply to get +-12VDC. Something like the attached image. I would get a rail splitter component but any way to save money is always a plus.

author: Benta
author_rank: Super Contributor
timestamp: July 26, 2025, 12:29:04 am
content: If you want to do this on the power supply rails, it's a terrible idea.Much better would be to AC couple input and output of the amp and DC bias the input with your circuit.

author: Obsidianxenon
author_rank: Contributor
timestamp: July 26, 2025, 12:32:12 am
content: That was my second option anyway so no worries.Out of curiosity, why is this a bad idea?

author: PCB.Wiz
author_rank: Super Contributor
timestamp: July 26, 2025, 01:01:01 am
content: Quote from: Obsidianxenon on July 26, 2025, 12:32:12 amThe impedance of that virtual ground is equal to the resistors in parallel, so quite high unless you waste a lot of power.Usually, a buffer is added after the resistors to lower the virtual ground impedance.

author: Obsidianxenon
author_rank: Contributor
timestamp: July 26, 2025, 01:02:16 am
content: Ah okay that makes sense now. I was wondering why that was the case with the buffers. Cheers.

author: Nei
author_rank: Newbie
timestamp: July 26, 2025, 08:58:32 am
content: Hi,Here is a simple and cheap headphone amplifier (in french) :https://www.sonelec-musique.com/electronique_realisations_ampli_casque_008.htmlCheers

author: Zero999
author_rank: Super Contributor
timestamp: July 27, 2025, 06:00:19 pm
content: TLE2426https://www.ti.com/lit/ds/symlink/tle2426.pdf

author: John B
author_rank: Frequent Contributor
timestamp: July 27, 2025, 09:01:36 pm
content: For DIY audio, one of the best ways is to use a dual winding transformer + rectifier + linear regulation.Depending on how you are building this, either point to point soldering or making a PCB, you may want to make the power supply a separate module for flexibility, then just feed your amplifier board with positive and negative rails, and GND.
12v strip led driver from lipo battery  - Page 1
Forum section: electronics / projects

author: metRo_
author_rank: Regular Contributor
timestamp: December 09, 2014, 11:43:16 am
content: Hello,I want to power a led strip from a lipo battery, so my input voltage with vary from 3.7 to 4.2v.I tried to found a led driver that meet my requirements but the only boost converter with constant current that I found that almost meet was ithttp://www.ti.com/product/lm3410but it need to connect to the Resistor that set the led current but in led strip the Resistor isn't accessible.Should I instead use a boost converter to 12v and then a led driver?What do you recommend?Thank you

author: ajb
author_rank: Super Contributor
timestamp: December 09, 2014, 03:33:27 pm
content: If your LED strip already has current limiting resistors built in, then you don't necessarily need a constant current LED driver; any 12V output converter will do. If you did want to use a constant current driver for some reason then you would need to add an external current sense resistor. Constant current converters are typically intended to drive LEDs or strings of LEDs that do not have current limiting resistors built in.

author: metRo_
author_rank: Regular Contributor
timestamp: December 09, 2014, 11:08:36 pm
content: I have read that a constant current controller improve led life time, that is the only reason I was thinking of a constant current controller.
12v to 32v Boost converter - Page 1
Forum section: electronics / projects

author: pyrohaz
author_rank: Regular Contributor
timestamp: January 28, 2014, 03:33:13 pm
content: Hey guys,I've never really done any form of power electronic design other than using a 7805 regulator and throwing in a few decoupling capacitors! So I thought it was time to give it a shot. After doing a generic ebay search, I found a few 100w LED's which require 32v at 1A, producing 7500 lumens! I'm sure it sounds as useless to you as it does me but I've decided to take on the task of running one of these bad boys on a 12v battery and designing my own boost converter!So far, I've thrown together a simple feedback based boost converter where the output (voltage/current?) is dependent on the current flowing through a series resistor with the LED. I'm simulating this in LTSpice and other than the initial transient, the circuit doesn't seem to be performing as I want it to!At the moment, I'm using "best case" components available on LTSpice (low ROn mosfet, efficient diode and universal op amps).Any help is appreciated!

author: fcb
author_rank: Super Contributor
timestamp: January 28, 2014, 03:53:26 pm
content: Is V2 generating a ramp? It looks like it generates a PULSE at the moment.

author: pyrohaz
author_rank: Regular Contributor
timestamp: January 28, 2014, 03:58:57 pm
content: Yep, the rise and fall time together make up the total period producing a triangle wave from 0 to 10v with a frequency of 50kHz.

author: Whales
author_rank: Super Contributor
timestamp: January 28, 2014, 10:11:14 pm
content: FYI your LEDs willnotreach 7500 lumens at 32 watts, rather something in the magnitude of 3000 lumens. This is stillverybright, and sounds like fun.Luminous efficacyof white LEDs only rises above 100 lumens per watt inpress releasesand at lower current levels. Generally LED sellers hideously over-state the output levels (think: all of dx.com LED torches) but 7500 lumensmightbe possible at the supposed 100W levels. Don't bet on it, however

author: granz
author_rank: Regular Contributor
timestamp: January 28, 2014, 11:11:20 pm
content: Well, I just quickly fired up your sim and it looks like you have 32V across the LED and ~1.25 A going through it. Isn't that what you wanted? (See the attached graph.) Your graph shows the feedback voltage only, so I'm confused about what you are asking...Cool project BTW.

author: pyrohaz
author_rank: Regular Contributor
timestamp: January 28, 2014, 11:18:12 pm
content: Quote from: Whales on January 28, 2014, 10:11:14 pmThanks for the reply! I think it was my fault in how I posed the question, I was hoping for some answers to why the LED didn't have the full 3A flowing through it. With a 0.33 ohm resistor and the reference voltage of 1v (and the differential amplifier having a gain of 10), surely the circuit should automatically adjust the pulse width to keep the voltage across the 0.33ohm resistor at 1v?And I included the feedback voltage to show that it wasn't equal to the reference voltage. Come to think of it, I probably should've plotted the LED current instead!
12V to -+ 6V  100mA per channel - Page 1
Forum section: electronics / projects

author: JoeyG
author_rank: Regular Contributor
timestamp: June 10, 2022, 12:13:37 am
content: Hi,To power an dual rail Op AmpWhat can you suggest for a simple 12V Vin to +-6V out reasonably regulated power supply ~ 100mA.I'm not anticipating an sharp transients.Low ripple would also be good

author: Someone
author_rank: Super Contributor
timestamp: June 10, 2022, 12:39:46 am
content: Here is a good resource to read through:https://sound-au.com/project43.htmhttps://sound-au.com/project192.htmAn awesome site with plenty to learn for people at all levels.

author: Zero999
author_rank: Super Contributor
timestamp: June 10, 2022, 06:50:28 am
content: A rail splitter is definitely the way to go. There's also the TLE2426, which is designed for this application.https://www.ti.com/lit/ds/symlink/tle2426.pdfWhat do the op-amp circuit do? If the signal is purely AC, i.e. audio, then bias the op-amps half the supply voltage and AC couple the inputs and outputs. Here are some examples of AC vs DC coupled op-amp circuits. Credit: audioguru for posting the original.
12V UPS - Page 1
Forum section: electronics / projects

author: phaseform
author_rank: Regular Contributor
timestamp: July 31, 2016, 08:57:20 pm
content: I am wanting to build a 12v UPS to run a RPi and 12v external HDD. I'm at the part of figuring out charging for an SLA battery. So I've got as far as thinking I need a constant current/constant voltage buck regulator set at 13.5V and some current limit to look after my SLA battery if the charge gets low.Thismodule looks like it may be perfect, if it's the same as the one inthisvideo. So I understand that if current limiting comes in the voltage will drop to accommodate. Here I'm thinking I will want a setup something like this:I *think* I just need to workout my current needs for my 12V regulator and make sure the current limit on the SLA CC module will be below the laptop PSU max power. But this has the problem of a 12 volt regulator connected after a diode to the SLA.. I'll also need low voltage cut-out for the SLA.. work in progress

author: tszaboo
author_rank: Super Contributor
timestamp: August 01, 2016, 10:21:53 am
content: Check, if the laptop PSU output is not a dead short if the mains voltage is disconnected.

author: oldway
author_rank: Super Contributor
timestamp: August 01, 2016, 10:48:20 am
content: In discharge, the battery voltage is more or less 12V and there will be only 12-0.6V = 11.4V at the 12v voltage regulator input.It is too little voltage even if it is a low drop regulator.

author: Rerouter
author_rank: Super Contributor
timestamp: August 01, 2016, 11:40:49 am
content: A car battery down to about 65% discharge should be greater than 12.6v if using an LDO, otherwise a buck boost could be used but you risk shortening the life of the battery by draining under 11.2v,

author: nowlan
author_rank: Frequent Contributor
timestamp: August 01, 2016, 12:19:35 pm
content: Stack it on some diodes to raise the 12v-drop?

author: tszaboo
author_rank: Super Contributor
timestamp: August 01, 2016, 02:09:17 pm
content: Quote from: oldway on August 01, 2016, 10:48:20 amNot that one, the laptop PSU. Unplug it and measure if the output. I had SMPS which became something like 2 Ohm impedance on the output if there is no mains.

author: phaseform
author_rank: Regular Contributor
timestamp: August 01, 2016, 04:12:35 pm
content: Thanks NAND I got a quick chirp from a diode test on my multimeter, not really sure if this would even be a problem on a power outage.I can perhaps use a second voltage regulator or whatever for my DC devices, I think shifting the circuit to this:would solve my battery charging worries, then I can just do whatever I want with the ~12-13.5 backed up supply. I knowthisregulator has a TTL power down, perhaps I can use a transistor on the power down pin to cut power at a certain battery discharge voltage.
12V/24V- 35-50A sealed connectors - Page 1
Forum section: electronics / projects

author: cs.dk
author_rank: Unknown
timestamp: November 07, 2018, 05:12:27 pm
content: Hi all,I've been browsing through catalogues with little luck.Something like Tyco/AMP SuperSeal series (in a larger version would be great).. But I can't seem to find something that meet the requirements.Does someone know a connector-type that would fit?

author: Gregg
author_rank: Super Contributor
timestamp: November 07, 2018, 10:34:41 pm
content: Try a search for Delphi weather tight connectors

author: timpattinson
author_rank: Contributor
timestamp: November 08, 2018, 12:47:15 am
content: Deutsch DTP connectors are rated 25A cont/pin if that's any helpSent from my SM-G930F using Tapatalk

author: PhysicsDude55
author_rank: Contributor
timestamp: November 13, 2018, 12:59:39 am
content: I know its overkill, but 50A twist lock receptacles, commonly used on RVs, generators, boats, etc. would do the trick.

author: Bratster
author_rank: Frequent Contributor
timestamp: November 13, 2018, 04:38:34 am
content: Quote from: PhysicsDude55 on November 13, 2018, 12:59:39 amThose connectors are not sealed so it would not apply to what the OP is asking for.Not to mention using a connector rated for,And commonly used for 120/240VAC, in an application for 12 and 24 volts DC is an absolutely terrible idea.Sent from my Fi Moto x4 using Tapatalk

author: cs.dk
author_rank: Unknown
timestamp: November 13, 2018, 04:56:23 am
content: It seems like the Delphi Metri-Pack series connectors fits wellThanks.
13.56 MHz RFID antenna multiplexer and antenna distance from reader IC - Page 1
Forum section: electronics / projects

author: ricko_uk
author_rank: Super Contributor
timestamp: July 15, 2024, 01:37:37 pm
content: Hi,I am working on a 3 x 3 matrix of 13.56 MHz RFID reading coils (different from another project I previously posted) and the reader for each coil is up to 20 cm away from the coils.Are there any potential issues on using a single RFID reader IC for all coils (instead of 9 - one for each coil) and multiplex the coils? I am thinking latency, but perhaps other potential issues?Thank you

author: ricko_uk
author_rank: Super Contributor
timestamp: July 20, 2024, 04:49:57 pm
content: Hi all,could someone please offer any suggestions or info about this? It would be much appreciated.Thank you

author: jpyeron
author_rank: Regular Contributor
timestamp: July 20, 2024, 09:16:55 pm
content: I have used a contractor in Argentina (chlab-design.com), maybe he can help you.
130 volt phantom power schematics for microphone - Page 1
Forum section: electronics / projects

author: Wiljan
author_rank: Regular Contributor
timestamp: July 26, 2020, 12:09:29 pm
content: HiA friend of mine got an old Bruel & Kjaer / DPA 4003 microphone which require 130 Volt phantom power.So I look for a schematic to create the 130v phantom instead of normal 48v to get it operating.Of course it would be possible with an oscillator and a Jacob ladder to make some high voltage but since it has to be use with a microphone level I believe it quickly will make some noise so any suggestion are welcome..

author: profdc9
author_rank: Frequent Contributor
timestamp: July 26, 2020, 01:07:17 pm
content: Since the current required is not likely very much, you can use one of the simple boost converters set up for Nixie tubes which generate 200 volts, but change the resistive divider to regulate to 130 volts.https://www.electronics-lab.com/adjustable-hv-power-supply-stompbox/It's not as efficient as designs using dedicated converter ICs but it can use very simple parts. The voltage is widely adjustable by changing the R5, R6, R7 voltage divider. I have used this design in several projects with success with voltages from 15 to 200 volts.

author: Wiljan
author_rank: Regular Contributor
timestamp: July 26, 2020, 06:13:28 pm
content: Quote from: profdc9 on July 26, 2020, 01:07:17 pmprofdc9 the Nixie PSU is a good idea there are a lot of "ready" modules on ebay for low money and as I could see on one the use a switch freq about 500kHz which should hopefully not interfere with the microphone (make noise).I will look into that idea for nowThank you

author: David Hess
author_rank: Super Contributor
timestamp: July 27, 2020, 05:42:44 pm
content: Quote from: Wiljan on July 26, 2020, 12:09:29 pmCharge pumps can be pretty low noise and especially so if driven with a sine wave.

author: Zero999
author_rank: Super Contributor
timestamp: July 27, 2020, 06:02:16 pm
content: Quote from: Wiljan on July 26, 2020, 06:13:28 pmThe amount of power required by a condenser microphone is so tiny, you could just leave it set to 200V and use a shunt regulator and filter to bring the voltage down to 130V.

author: eliocor
author_rank: Unknown
timestamp: July 27, 2020, 10:11:04 pm
content: as always, I suggest the complete reading of LT AN 118 (Jim Williams):https://www.analog.com/media/en/technical-documentation/application-notes/AN118fb.pdf

author: Wiljan
author_rank: Regular Contributor
timestamp: July 28, 2020, 10:33:28 am
content: Quote from: David Hess on July 27, 2020, 05:42:44 pmYes I'm aware of that, thank you

author: Wiljan
author_rank: Regular Contributor
timestamp: July 28, 2020, 10:34:34 am
content: Quote from: Zero999 on July 27, 2020, 06:02:16 pmThat's a good way to filter the noice away, thank you

author: Wiljan
author_rank: Regular Contributor
timestamp: July 28, 2020, 10:35:38 am
content: Quote from: eliocor on July 27, 2020, 10:11:04 pmThank you for the link, it's a very informative app note on the subject
135 and 900 ohm devices? - Page 1
Forum section: electronics / projects

author: coppercone2
author_rank: Super Contributor
timestamp: May 04, 2021, 06:37:41 am
content: So I have a HP impedance match device that does 135, 600 and 900 Ohms. 600 I kind of get, it seems pretty common,but what the hell are 135 and 900 ohms used for? Does anyone have a history of these impedance values ? Does anything interesting use them?

author: bob91343
author_rank: Super Contributor
timestamp: May 04, 2021, 05:23:19 pm
content: I don't think so. They are probably there because it was easy and makes it look like the unit is more versatile.

author: Terry Bites
author_rank: Super Contributor
timestamp: May 04, 2021, 06:38:52 pm
content: Ask a telephone man: Characteristic impedances of 600 Ω for home wiring and 900 Ω for central office wiring. IDSN filters 135 ohms @40kHz

author: coppercone2
author_rank: Super Contributor
timestamp: May 04, 2021, 08:14:18 pm
content: why does it change like that? I guess ISDN is more similar to 50 Ohm, but why 900 and 600? Then again the ISDN frequency is really low too, so I have no idea why any of this is done.

author: srb1954
author_rank: Super Contributor
timestamp: May 04, 2021, 08:36:28 pm
content: Quote from: coppercone2 on May 04, 2021, 08:14:18 pmThe characteristic impedance of a twisted pair telephone cable is typically around the 120-130range at the higher frequencies where ISDN works. The impedance of a twisted pair cable varies considerably throughout the audio band and is higher at lower frequencies.The 600figure was the approximate characteristic impedance for early open wire telephone lines.

author: coppercone2
author_rank: Super Contributor
timestamp: May 05, 2021, 02:31:06 am
content: why have 2 different types of cable?

author: srb1954
author_rank: Super Contributor
timestamp: May 05, 2021, 07:39:54 am
content: Quote from: coppercone2 on May 05, 2021, 02:31:06 amOpen wire lines for putting on top of telephone poles.Twisted pair cables for burying in the ground.

author: bsdphk
author_rank: Regular Contributor
timestamp: May 05, 2021, 09:21:24 am
content: Quote from: Terry Bites on May 04, 2021, 06:38:52 pmGiven the vintage of these devices, I also have one, it would not have been for ISDN but for carrier systems.
14-Ton Compression Crimp Cross-Section Photos - Page 1
Forum section: electronics / projects

author: sonicj
author_rank: Frequent Contributor
timestamp: October 26, 2011, 05:49:26 am
content: thought some of you guys might be interested to see the insides of a high current compression connection... these cross section photos are of a 2/0 compression lug i crimped some time back.cable: 00AWG (2/0, 133kcmil) carolprene welding cable. 1248 30awg strands. EPDM jacketlug: t&b black 45 double banddie: t&b black 45 hexhydraulic psi: 10,000output force: 14-tonspics 1 & 2 show the barrel end of the severed lug as i found it in my yard nearly a month after it was removed. pic 3 was after cutting with a dremel followed by cleaning up with a grinder. pics 4-6 show the cross-section after sanding smooth followed by a quick polishing. enjoy!-sj

author: Time
author_rank: Frequent Contributor
timestamp: October 26, 2011, 06:16:13 pm
content: Interesting. I have been using some crimp lugs on 4/0 lately with a pnematic hex crimper. Kind cool to see what happens inside.

author: slateraptor
author_rank: Frequent Contributor
timestamp: October 27, 2011, 05:51:57 am
content: Someone obviously had waaaaaaaay too much time on his hands.

author: Balaur
author_rank: Unknown
timestamp: October 27, 2011, 06:45:13 am
content: Hey, very nice photos. I absolutely love to see how the crimp force put everything together in a nice lump.Thank you for the time and effort to prepare the photos.Cheers,Dan

author: sonicj
author_rank: Frequent Contributor
timestamp: October 27, 2011, 07:12:23 am
content: Quote from: Time on October 26, 2011, 06:16:13 pmindeed!i don't recall any t&b literature referring to "cold welding" of the copper, so thats the next thing i'd like to figure out. are the strands & lug still separate? or are they now one solid piece of copper? unfortunately, i lost the other half somewhere in the shop, and think this half might become a keychain.Quote from: slateraptor on October 27, 2011, 05:51:57 ami actually took these photos for a crimp vs solder debate on another forum. some people like to argue religion, some people like to argue cable termination. lol!-sj

author: slateraptor
author_rank: Frequent Contributor
timestamp: October 27, 2011, 05:30:38 pm
content: Quote from: sonicj on October 27, 2011, 07:12:23 amLOL well defended
1/4" TRS With LED? - Page 1
Forum section: electronics / projects

author: LydaRA
author_rank: Contributor
timestamp: April 30, 2021, 03:58:00 pm
content: This may be a bit odd, but has anyone seen a 1/4" TRS connector with a built-in LED? (Or like a three-pin variant of a Dell laptop power adapter with that glowing blue ring on the DC plug hood?)I'm designing a new model rocket launch controller for the Cub Scouts. Thinking of how to make removable "keys" that also indicate circuit status....and also harder to spoof.A 1/4" connector seems about the right size, not too small and easy to lose, but not too large and a pain to carry 16 at once.Using a TRS/stereo type, so as to have both positive and negative sides of the circuit....and an extra contact in-between. If the Scout inserts the valid connector, we'll have the tip and sleeve wired together, and it'll work. But if they try sticking a pocket knife, wire, whatever into the jack; the tip will short to the ring and tell the controller to lock-out!Don't know that I've seen such a connector, with an LED. But before I take on building one, thought I'd ask the community to share if they know of one. Or are there other ideas for such a removable circuit "key?" Thanks in advance.

author: Buriedcode
author_rank: Super Contributor
timestamp: April 30, 2021, 04:24:32 pm
content: You should be aware that TRS connectors could possibly short contacts on insertion. If your tip and sleeve are wired, then upon insertion depending on the socket, you could possibly short the sleeve and ring before it is fully inserted, causing a false negative/lockout. One of the reasons TRS isn't suited to any kind of power connection. I'm sure many sockets will only have solid connections when the plug is fully "in", but you will have to fully test the sockets you're using.Although it adds complexity, you could always wire some resistors as a voltage divider for the three contacts, with the device using a uC with an ADC or just a comparator to check the resistor ratio. They would easily fit inside a small TRS serso plug, and would mean you're not looking for a short/open type situation, but rather something more specific. It also means if needs be, you could use different resistor ratios for different keys. Hardly high-tech security, but simple and not easily spoofed - and can't be fooled with a screwdriver like some kind of dead-short would be.

author: oPossum
author_rank: Super Contributor
timestamp: April 30, 2021, 05:01:03 pm
content: Just measure Vf of the LED. Much less chance of a false key detection.

author: LydaRA
author_rank: Contributor
timestamp: May 01, 2021, 12:56:23 am
content: Very good point and idea, BuriedCode. Thanks.There is another part of the circuit, a button, that has to be pressed simultaneously to trigger the launch. So we really don't need to try reading the presence & validity of the "key," until the flip covered button is activated. But definitely a good consideration to document.
14/28v Variable DC load bank - Page 1
Forum section: electronics / projects

author: Lackuwaxa
author_rank: Newbie
timestamp: May 03, 2016, 05:28:12 am
content: Hi guys,I am trying to design a DC load shedding circuit that can dissipate upto 70A (1960W at 28V, 980W at 14V), ideally i want it to be variable, able to ramp from 5-100%.My first thought, and the easiest way, is to use 4 seperate loads individually switched each of about 15A. This is a very clunky way to do it and I am not super psyched to do it this way. My load resistors are 100W8R in parrallel (4 resistors to give us 400W2R 14A at 28V 392W). The problem comes with so many in parallel, the resistance drops to around 0.4ohms to drop 70A at 28V which means there is no way i can make it variable with a simple 100W50R pot.I am thinking that a PWM control circuit is the only way that I can make it variable, but I dont know enough about how to design the circuits. I have searched the internet, but there are so many different circuits that i am lost. The fet needs to be able to take upto 80A (max 65A but with termal head room).The last question is in regards to heat dissipation, i have 4 24V DC fans that I am going to put 2 at each end of the enclosure, the power resistors will each be mounted on an ally plate that will be fixed to a heattsink .. not sure how to calculate if this will be enough to disapate te heat or not.if anyone has a better idea on how to achieve tthis i am all ears.cheers for readingWade

author: Cloud
author_rank: Regular Contributor
timestamp: May 03, 2016, 03:13:48 pm
content: Absolutely no PWM, because you need constant load. You can use multiple fets in parallel.

author: ZeTeX
author_rank: Frequent Contributor
timestamp: May 03, 2016, 06:58:12 pm
content: Quote from: Lackuwaxa on May 03, 2016, 05:28:12 amThe op amp constant current sink like this one:Will just need some changes in the circuit and it will work.problem is the heat - you are going to need probably a shit ton of mosfets and a giant heatsink.traces are going to be also very wide.
15 W Qi charger selection help - Page 1
Forum section: electronics / projects

author: mgwalker95
author_rank: Contributor
timestamp: July 22, 2020, 01:54:40 am
content: Hi,I am trying to integrate a 15W Qi MP-A11 charger into a project of mine, but I am having issues finding the correct part. Has anyone found a 15W Qi MP-A11 they would recommend?I am currently using a P9242-R for my Qi transmitter and it is working but does not charge Iphone's and Samsung phones up to the 7.5W that it should be able to, it is only charging them at 5W. I suspect that this is because the P9242-R is a MP-A2 transmitter type. All the Iphone/Samsung 7.5 W chargers that I am seeing are transmitter type of MP-A11 or MP-A11a.The only 15W MP-A11 transmitter Reference design/IC that I have found online is WCT-15W1CFFPD(IC: MWCT1013VLH), but they do not have any of the boards in stock and the schematic is not posted anywhere online.Also I have been reading the Qi spec and I do not quite understand the difference between the MP-A2 and MP-A11 transmitter design?it seems to me that any transmitter design can transmit 5W but the Extended power profiles must have a specific type for each RX. is this correct?Do yall have any thoughts?Regards,Michael

author: mgwalker95
author_rank: Contributor
timestamp: July 22, 2020, 04:47:41 am
content: After doing some more digging i was able to find XMC6521SC-Q040X with REF_10WTX_QI_4102 refrence board, But this board does not have a reference schematic posted or firmware posted.

author: mgwalker95
author_rank: Contributor
timestamp: July 23, 2020, 12:28:43 am
content: Apple apparently does not follow the Qi standard for their 7.5W which is why my charger does not work at 7.5W.source:https://www.zdnet.com/article/iphone-and-android-wireless-charger-pads-which-one-is-the-best/

author: mgwalker95
author_rank: Contributor
timestamp: July 23, 2020, 01:07:37 am
content: Another source:https://9to5mac.com/2017/11/14/iphone-fast-wireless-charging/#:~:text=Right%20now%2C%20all%20wireless%20charging,and%20Mophie%20Wireless%20Charging%20Base."only companies that partner with Apple (like them) will be able to be certified and have their Qi chargers take advantage of the 7.5w power output."
1500v and 10ma,  how too drive transistors base's - Page 1
Forum section: electronics / projects

author: patrick1
author_rank: Contributor
timestamp: August 06, 2019, 05:21:30 pm
content: hi guys, im trying too build my own opto isolators, because i need a base driver with incredible ruggedness.this version of my h-brigde ,is 10w led's triggering garden solar light panels, using chipstick and hotglue.amusingly the prototype worked very well, so i got some bigger solar cells from bunnings.but i dont know if it is possible too determine the BASE current requirements for my 1000v, 10ma motor. (base drive requirements,)feel free too laugh, ~~ i am ;-Dhttps://pasteboard.co/IrsWWiB.jpg

author: patrick1
author_rank: Contributor
timestamp: September 23, 2019, 02:53:57 pm
content: Well I have some more Data for my Question ;Q ; How much drive current is required keep a Base Junction Charged. when driving my motor @ 1000v and between 1 and 20 maFirst hotglue prototype as mentioned above, resulted in lost torque from the motor,Second prototype as below, with green LED's and upgraded solar panels for gate drive, has restored the lost mechanical torquepictures of the apparatus @ 11minsthe gate drive coming out of the solar panels, has now increased too 13ma shorted. and 4.5volts open circuit.
150A PCB aluminium or FR4 - Page 1
Forum section: electronics / projects

author: strawberry
author_rank: Super Contributor
timestamp: January 16, 2021, 11:19:27 am
content: custom >150A BLDC driver:aluminium 35um with soldered copper busbars + control PCBFR4 4layer 35um with soldered copper busbars and soldered vias under MOSFETor TH with soldered copper busbars TO247is aluminium PCB best for the job?

author: Terry Bites
author_rank: Super Contributor
timestamp: January 16, 2021, 02:52:56 pm
content: You're scaring me man.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: January 16, 2021, 02:57:55 pm
content: Can't see much advantage of ali. PCB here, and will be hard to solder the busbars.It does depend how much dissipation you're expecting to see on the MOSFETs

author: jmelson
author_rank: Super Contributor
timestamp: January 16, 2021, 04:09:26 pm
content: Quote from: strawberry on January 16, 2021, 11:19:27 amYou can use a PCB for the control side of things. Generally, in this power class, they use huge power bricks and there is very LITTLE power "wiring".The junctions of the high- and low-side transistors come out to 3 screw terminals and go straight to the motor. The DC capacitor bank have 2 screw terminals and go to plates that connect a bunch of aluminum electrolytics.Jon

author: strawberry
author_rank: Super Contributor
timestamp: January 16, 2021, 05:33:38 pm
content: chinese use aluminium PCB for advertised 100Aif aluminium board have sufficient thermal resistance in practicemodules are expensive
150V 1A voltage booster - Page 1
Forum section: electronics / projects

author: xmen
author_rank: Newbie
timestamp: November 19, 2017, 06:06:35 am
content: There is a DC-DC boost module that can deliver upto 10A. But it can only do 80V max and my question is, can I modify it to increase the output voltage upto 150V. And only draw 1A.Since this module uses UC3843, I believe I can modify the resistor values to adjust the output. But before I do that, I would like to know, will there be any problem ?Input voltage is 24V.here is the link to modulehttps://www.ebay.com/itm/10V-60V-to-12V-80V-600W-10A-Boost-DC-DC-Converter-Power-Supply-Step-up-Module/222649153345

author: Seekonk
author_rank: Super Contributor
timestamp: November 19, 2017, 07:00:39 am
content: I have wound extra turns on the coil and added a second rectifying section to get more voltage. It may say 600W, but if you read the specs further, the chance of getting 150W are dubious. What voltage are you starting from? I was slumming ebay the other day and found these. Not regulated but interesting for some applications.https://www.ebay.com/itm/50Hz-Power-Frequency-Transformer-Inverter-Drive-Circuit-Board-Module-DC12V-300W/263321339801?_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D49451%26meid%3D6653e8fea8b3450fa4e2b16b987ed21c%26pid%3D100678%26rk%3D3%26rkt%3D15%26sd%3D252115976793&_trksid=p2481888.c100678.m3607&_trkparms=pageci%253Aeddb3829-ccf5-11e7-8742-74dbd1807f16%257Cparentrq%253Ad30aea0415f0abda4a8ab593fffbd8c2%257Ciid%253A1There are some cheap 3525 + 358 driver boards that can also get you a good start.

author: xmen
author_rank: Newbie
timestamp: November 19, 2017, 10:22:44 am
content: Quote from: blueskull on November 19, 2017, 06:25:05 amVery good, I will look at them as well.Quote from: Seekonk on November 19, 2017, 07:00:39 amAccording to specs on other locations, it can do 240W output with 24V input. Which is quite enough I believe.

author: Seekonk
author_rank: Super Contributor
timestamp: November 19, 2017, 04:22:41 pm
content: There you go, problem solved. Come back and tell us how it works out for you.
150V Boost converter with LM2588 (Choke vs transformer) - Page 1
Forum section: electronics / projects

author: Pack34
author_rank: Frequent Contributor
timestamp: May 16, 2016, 08:22:42 pm
content: I'm working on a 150V boost converter. I want to test a design using the LM2588 flyback regulator from TI and I have a question regarding the transformer. I've never actually designed anything using one so bear with me.I was wondering if I could substitute a choke instead of the transformer and flip the polarity of the second coil to agree with the output current flow of the circuit. Is this correct?LM2588http://www.ti.com/product/LM2588Webbench of the projecthttp://webench.ti.com/webench5/power/webench5.cgi?origin=ti_panel&lang_chosen=en_US&VinMin=5&VinMax=5&O1V=150&O1I=0.033&op_TA=30Choke I want to usehttp://katalog.we-online.de/pbs/datasheet/74489430220.pdf

author: Monadnock
author_rank: Contributor
timestamp: May 16, 2016, 08:28:29 pm
content: If you want to stick with the LM2588 you will have to stick with a transformer. The internal switch of that part is only rated for 60V.In a boost converter you need a switch equal to the output voltage, plus some margin. So you are looking at a 200-250V switch.

author: Pack34
author_rank: Frequent Contributor
timestamp: May 16, 2016, 08:37:56 pm
content: Do you have a suggestion for the controller? A transformer would be way too big for this application.I'm using a very high estimation for the output current. I only really need a couple milliamps on the output.TI's webbench seems to be pushing me towards the LM258X series controllers. I wanted to use the LM3478 but it doesn't seem to handle the boost from 5 to 150V.

author: Monadnock
author_rank: Contributor
timestamp: May 16, 2016, 08:49:19 pm
content: You need to use something with an external switch like this:http://www.linear.com/product/LT3757
15mhz phase locked vco/oscillator??? - Page 1
Forum section: electronics / projects

author: CaptDon
author_rank: Super Contributor
timestamp: September 21, 2020, 02:30:24 pm
content: I would like to phase lock a 1mhz oscillator to the WWV 15mhz signal.I have a nice narrowband 15mhz front end with agc and a nice 15mhzat 200mvpp output under most band conditions. Could I inject the 15mhzwithout a 15:1 divide chain directly into a 4046 running at 1mhz and expectit to maintain some sort of lock condition? I was also thinking of a 1mhzcrystal controlled oscillator with a trimmer capacitor that was free runningperhaps 1 or 2 hertz slow and 'push' it with my 15mhz signal to maintainsynchronized oscillation like the color oscillator in the old NTSC T.V. sets.Perhaps a dual gate fet for the injected oscillator? Any ideas? The goal isa WWV locked 1mhz lab reference without doing the 'GPS Disciplined'option. WWV 5mhz and 10mhz are not usable in my lab do to ethernetcabling leakage and local interference. 15mhz is a 5/9 signal most of the day.

author: Benta
author_rank: Super Contributor
timestamp: September 21, 2020, 06:24:35 pm
content: For frequecies in that range, forget the 4046 or 74HC4046.The VCOs will play along, but the PFDs won't; you'll have significant jitter. Not because the parts are bad, but it's just the nature of PFDs. The propagation delays through them are just a fact of life.You need to look elsewhere. I can suggest the ON Semiconductor parts:MCK12140MC100EL1648But I'm certain other suppliers also have ICs for this.
-15v contrast supply for Graphics LCD - Page 1
Forum section: electronics / projects

author: djsb
author_rank: Super Contributor
timestamp: November 13, 2010, 02:35:24 pm
content: I need to supply a -15V voltage to the contrast pin on a Graphics LCD. I have discovered the following options for myself.1/ Feed a 100Khz PIC pin output into a diode charge pump.2/ Use the -9v output of a MAX232 transceiver (if fitted).Are there any easy DC-DC convertor solutions I can use or any other straightforward solutions. I know I should have bought a LCD module with the negative voltage convertor built in but you live and learn.David.

author: allanw
author_rank: Frequent Contributor
timestamp: November 13, 2010, 03:18:17 pm
content: Currently I'm using TC962 in a project to generate -15V. It's a beefier version of the smaller TC7662.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: November 13, 2010, 04:01:21 pm
content: I wouldn't advise using output of max232 as you may find voltage will change when transmitting, causing screen flicker.Charge pump from a PWM output on PIC is the cheapest if you can get sufficient current- you could also PWM it for contrast control. There are several standalone charge pump chips out there. Good old 555 timer + charge pump is another option.

author: NiHaoMike
author_rank: Super Contributor
timestamp: November 14, 2010, 11:31:34 pm
content: How much current do you need? If it's a few mA or less, the charge pump is probably the best way. You could actually drive the charge pump from the MAX232 and use a simple shunt regulator.

author: Psi
author_rank: Super Contributor
timestamp: November 15, 2010, 12:53:39 pm
content: You can also buy tiny power supply modules in DIP/SIP type packages.You could either get a -15v one or a +15v isolated one.It wont be the cheapest option but will probably be less expensive than your thinking.Also it will look nice and be real easy to implement.here's two real quick example of ones at digikey, +5v input -> isolated 15v output.Link + output to your gnd and you have -15v on the - outputUSD$4.98http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=945-1222-NDUSD$6.70http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=102-1362-NDThey cant handle huge capacitive loads though, dunno if that will be a issue for your application or not

author: Zad
author_rank: Super Contributor
timestamp: November 22, 2010, 02:36:42 pm
content: How about a classic 555 followed my a voltage multiplier? For low current applications like yours it is easy enough to add more multimplier stages:This is the generic multiplier schematic, invert the diode orientation for a negative voltage generator:

author: oPossum
author_rank: Super Contributor
timestamp: November 22, 2010, 02:42:38 pm
content: ICL7660App Notes(See page 9 for -15V)