hybridfree/eevblog-posts huggingface dataset:
Battery PSU on the bench. Schematic? - Page 1
Forum section: electronics / projects

author: neazoi
author_rank: Newbie
timestamp: December 26, 2011, 01:09:35 pm
content: Hello,The battery is the cleanest PSU of all and for RF and small signal work this does matter. Since some of my projects are based on RF stuff, I mainly experience the effects of non-battery based PSUs on them, so I have decided to build a lead acid battery PSU that will be able to handle a few Amps.Is there anyone that has done this before? Any schematics?I am interested in a variable PSU. I think I am going to connect two lead acid 12v batteries in series, so I can obtain a negative-GND-positive rail.Two main issues here. How should I adjust the voltage of this negative-GND-positive rail, so I can have a variable voltage PSU?Also can current limiting be applied and how?Will the "cleanness" of this battery PSU be affected by the series regulator or not?

author: Unknown
author_rank: Unknown
timestamp: December 26, 2011, 01:41:16 pm
content: You can just use any lab supply schematic that works with DC input, like the one Dave recently presented. The most flexible would be to build it twice, one for each battery. You can then connect the outputs in series and optionally ground one of the terminals. The regulators and opamps will each add some amount of noise, see datasheet.
Battery question please ? - Page 1
Forum section: electronics / projects

author: Peter3
author_rank: Newbie
timestamp: April 29, 2017, 05:59:55 pm
content: Hello.Some years ago my sister and I both purchased remote door bell sets fromour local shops, different manufacturers from different shops. In each casethe main unit was powered by three AA batteries.Both units failed after a short period and in both cases it was found that themiddle one of the three batteries had discharged to a point that the unitwould no longer function. In addition to this, it was found that in one casethe battery had not only discharged but had also reversed its polarity.Is there any precedent or known reason for this please?All on topic replies will be welcomed.Thank you, Peter3

author: Kilrah
author_rank: Unknown
timestamp: April 29, 2017, 06:02:39 pm
content: Would be interesting to tear it down and see how things are wired.

author: Peter3
author_rank: Newbie
timestamp: April 29, 2017, 06:28:53 pm
content: Thanks for your reply.We junked them shortly afterwards and purchased better quality units but thequestion still remains.Regards Peter3.

author: Kilrah
author_rank: Unknown
timestamp: April 29, 2017, 06:43:37 pm
content: Will be a lot harder to find the reason then...First thing that comes in mind is that they used only one of the cells for standby power, and the 3 in series only for the gong.That's terrible design, but I've seen that a few times.

author: Zero999
author_rank: Super Contributor
timestamp: April 29, 2017, 07:35:35 pm
content: If one cell was weaker than the others, then it can discharge and then recharge in the reverse direction, which can cause leaking and mess.It might be a coincidence or the two doorbells could do as Kilrah said: use one cell for standby, therefore discharge it more than the others.

author: Peter3
author_rank: Newbie
timestamp: April 29, 2017, 08:36:29 pm
content: Thank you both for your replies.I see what you mean and it would not surprise me at all if that was the case.Certainly a very likely explanation.Thank you Peter3

author: akis
author_rank: Frequent Contributor
timestamp: April 30, 2017, 06:40:32 am
content: Quote from: Peter3 on April 29, 2017, 05:59:55 pmMiddle battery placed or wired in reverse by accident?

author: Peter3
author_rank: Newbie
timestamp: April 30, 2017, 08:39:27 am
content: Thank you Akis for your reply.It is now suggested that the manufacturers of the cheaper units have, in the past,wired the batteries to use one for the standby then all three to sound the chime.If so, this would explain why one battery goes down first, resulting in not enoughpower to sound the chime.Thank you again Peter3
battery retainer for coin cell diameter 12.4 mm, height 5.4 mm - Page 1
Forum section: electronics / projects

author: mssp
author_rank: Newbie
timestamp: September 07, 2023, 10:06:35 am
content: I'm looking for a battery retainer/holder for soldering on a PCB. There thousands for flat coin cells but I cannot find any for Varta CP1254 with diameter 12.4 mm, height 5.4 mm. Does anybody know a source for a few units?

author: tooki
author_rank: Super Contributor
timestamp: September 07, 2023, 10:24:33 am
content: How about Keystone 501, intended for two 2.5mm thick cells?

author: mssp
author_rank: Newbie
timestamp: September 07, 2023, 11:57:52 am
content: dual cell is a great idea, will definitely try Keystone 501.
Battery simulator 12v 5Aish ? - Page 1
Forum section: electronics / projects

author: digsys
author_rank: Unknown
timestamp: February 03, 2017, 03:00:03 am
content: There are a lot of old posts on this but just seeing if there was something new -Anyone find a reasonable priced Battery simulator ? or 2 quadrant P/Supply ? working design ? - few hundred $?There's heaps of expensive options out there
Battery spot welding strip advice. - Page 1
Forum section: electronics / projects

author: drummerdimitri
author_rank: Frequent Contributor
timestamp: June 05, 2019, 10:11:36 pm
content: So I am looking to start spot welding 18650 batteries for some project and have no idea if there is a standard width and thickness for 18650 battery strips.I've seen widths from 4 to 10 mm and thicknesses from 0.04 mm to 0.3 mm.Will be buying a 10 m roll for future use and found a source of pure nickel strips instead of mostly nickel plated steel found on the market.There is no harm in going for a thicker strip right? Just a cost and weight penalty?What do you recommend?

author: Rerouter
author_rank: Super Contributor
timestamp: June 06, 2019, 02:14:42 am
content: Thicker requires a more powerful spot welder. Wider is OK. But you generally do not want to go wider than the battery ends.The smaller stuff is easier to work with because it deforms pretty easily. Just sometimes harder to line up the welder
Battery stack cell voltage measurement - Page 1
Forum section: electronics / projects

author: Centmo
author_rank: Contributor
timestamp: October 28, 2013, 08:33:10 pm
content: Hi, I am trying to accurately measure (1mV accuracy is my target) the voltages of every cell in a 14-cell LiPo pack. At 4.2V/cell, this is a maximum voltage of 58.8V, or about 60V. Currently, I am using voltage dividers (ratio ~1:20), into MUXes, and then into 12-bit 3.3V ADC inputs of my microcontroller. With this setup, each bit in the ADC represents a 15mV change, so this is the best-case accuracy with this method, which sucks.I have been doing some research, and found that an op-amp method of measuring the cell voltages is much more accurate (see attached). The problem is that I can't find any suitable op-amp ICs which can handle up to 60V. All the small, affordable quad-op-amp ICs seem to top out at about 44V. There are some single op-amp ICs which can handle this voltage, but they are large, built for high current, and expensive (especially if I need 14 of them).Any ideas?Thanks.

author: Andreas
author_rank: Super Contributor
timestamp: October 28, 2013, 08:49:16 pm
content: The LTC2057 (HV) is a very precise high voltage op amp.(available at DigiKey).Usually specialized (stackable) integrated cirquits are used for this purpose.TI, Intersil and LT have parts which include a ADC + cirquitry for balancing the cells.with best regardsAndreas

author: NiHaoMike
author_rank: Super Contributor
timestamp: October 28, 2013, 10:52:41 pm
content: LT makes a chip specifically designed for monitoring high voltage batteries.

author: Centmo
author_rank: Contributor
timestamp: October 28, 2013, 11:36:35 pm
content: Thanks for the replies.Andreas: thanks for the tip on the LTC2057. They're a little pricey to use exclusively ($2.54 * 14 = $35.56), but could be used for only the higher-voltage cells, while a cheaper op-amp can be used for the lower voltage cells.NiHaoMike: yes, I think I will end up going with one of the special chips designed for this, as I think it will end up cheaper in the end.
Battery tester board design considerations - Page 1
Forum section: electronics / projects

author: Saitama
author_rank: Contributor
timestamp: August 20, 2025, 11:25:02 am
content: Hi, I've been working on a battery tester project for a while now. I made the circuit and layout in KiCad and made my first functional single-layer board with toner transfer method, which turned out better than I thought. But as every other project, I want some improvements, like a larger 2.4" display with touch, a rotary encoder, extra buttons or a keypad and most importantly, to move everything to an ESP32, which seems a bit daunting, since I haven't really played around with them and am nervous about having to mess with the libraries. So before diving into all of that, I wanted to run the circuit by people more experienced than me.I have a couple of concerns with the current design:1) My power rail is awful. I am using the USB port from the arduino as power supply, which gets around 4.5V from my laptop, but measuring directly on the Op-Amp or other ICs shows 3.5V. Thankfully, all of the ICs and modules work with 3.3V, however the current sink is limited by the max output voltage of the LM358 and I cannot get the full scale.2) The device is going to be powered from a battery, which will need a boost converter to get the desired 5V and in my experience those cheap boost converters are unstable, noisy and outright unreliable. To mitigate that, I was thinking of using 2 in series for nominal 7.4V and linear regulators for the different voltage levels.3) I think the relays are drawing too much current. When both of them are on, the whole circuit draws around 120mA, which is a bit too much if the project is going to be battery powered.4) There isn't any reverse polarity protection. A diode is out of the question, due to low voltage of batteries and P-channel mosfets require more Vgs than I will probably get.Note that I am working with parts I have at hand or can source locally, which significantly limits my choices. The Tl431 and LM358 are examples of that.I will attach some photos and the code to this post, but I would be glad to send you more info or clarify anything you find odd.

author: Saitama
author_rank: Contributor
timestamp: August 20, 2025, 11:38:01 am
content: Clearly, there is a different tag for codeI will add a text file to this reply containing the code and some extra pictures.

author: BILLPOD
author_rank: Frequent Contributor
timestamp: August 20, 2025, 01:31:08 pm
content: Good Morning Saitama, Could you list the battery parameters your tester will be checking? Thanks

author: Saitama
author_rank: Contributor
timestamp: August 20, 2025, 01:34:48 pm
content: Good morning to you tooI'll mainly be testing 18650s and some li-po 1s batteries, but I don't think there is going to be much problems even with 12v ones, since the INA226 can handle up to 28V.
Battery tester negative voltage protection - Page 1
Forum section: electronics / projects

author: stepanoplustil
author_rank: Newbie
timestamp: January 14, 2021, 02:25:44 pm
content: Hello,I'm doing AA battery tester project to school. It is based on STM8S MCU. My task is to prevent people from placing the battery in opposite direction. Mechanically it's impossible. So I have to prevent voltage from getting to MCU pin. Thats the easy thing (using schottky diode and resistor). But I also have to show on display that the battery is being placed in wrong direction. So my thought is to tell to another MCU pin this information (analoge or digital - I have enough pins left). I'm looking for some simple circuit which gives 0V when the battery is in right direction and voltage >0V when it's placed wrong. I've tried many circuits (in simulator) and nothing works.One of the thought was to use op-amp as an inverting amp. with asymmetrical power supply (same as for the MCU) so it will do what I need. The problem was propably that the opamp and rest of my circuit shared ground. I don't know exactly why but it just didn't work. The next problem is that I'm using pretty small MCU that doesn't have separated ground for power and ADC converter. Otherwise the op-amp theory was able to been used (I think).I'm attaching my scheme here. AIN is the analoge reading pin on MCU, GPIO is used for turning on the N-MOSFET (loading the battery is also my task). The R3 10k is pull-down resistor when no battery is connected. Battery holder will be soldered directly to J2 BAT pins.Do you have any ideas how to solve this problem? Anything helps. Thanks a lot!

author: fordem
author_rank: Regular Contributor
timestamp: January 14, 2021, 03:09:52 pm
content: Curiosity question - how will the tester get power to operate the display when the battery is in backwards?

author: ledtester
author_rank: Super Contributor
timestamp: January 14, 2021, 03:32:24 pm
content: How about checking if the BUT (battery under test) is capable of driving a transistor? If the base is reversed biased wrt the emitter the transistor will be off. You can detect whether the transistor is on with another GPIO. Using a BJT it wouldn't be able to distinguish between a really flat (< 0.6V) battery and a reversed biased one. Maybe you could do something with a P-channel MOSFET.

author: eliocor
author_rank: Unknown
timestamp: January 14, 2021, 04:24:05 pm
content: Just an idea (only if you have to test ONE AA battery):R1/R2 make a voltage divider: 1/2 of VccRL is the battery load (about 1mA)When no battery is connected A/D reads 1/2VccWhen battery is connected A/D reads 1/2Vcc+1.5V or 1/2Vcc-1.5VVoltage range of the A/D converter is in range (if Vcc is from 3.3V to 5V) and you can determine if battery is in correct or wrong position.As a bonus your battery is checked with a load (1mA)
Battery Tester with Switching Ranges Using Series Resistors - Page 1
Forum section: electronics / projects

author: zohbou
author_rank: Newbie
timestamp: January 29, 2025, 01:05:29 pm
content: Hello, everyone!I’m working on building a battery tester. The idea is to charge and discharge the battery while measuring the current using a shunt resistor on the high side.I’ve placed two resistors in series for high and low ranges (amps and microamps) and the hole range -20A,to 20A , but I’m facing an issue. I want to bypass the low-range resistor using a MOSFET with a low RDS(on)​. However, I’m unsure if this is feasible because the source voltage can go up to 24 volts and if im in the amp range mosfet will always on .If anyone can help me with this or suggest an application note or reference design that I can use for inspiration, it would be greatly appreciated.Thanks!

author: xvr
author_rank: Frequent Contributor
timestamp: January 30, 2025, 12:36:53 pm
content: You can use P-Channel MOSFET and connect its Gate to ground to turn on bypass. N-Channel will require floating power source to control it (or something like this)

author: inse
author_rank: Super Contributor
timestamp: January 30, 2025, 03:39:34 pm
content: Why are you doing it on the high side?Things would be easier on the low side…

author: zohbou
author_rank: Newbie
timestamp: January 30, 2025, 04:09:38 pm
content: I already have a shunt resistor for measurement and to sink current, The current measurement needs to be performed on the high side.
Battery Testing service in Australia - Page 1
Forum section: electronics / projects

author: tomshirvo
author_rank: Regular Contributor
timestamp: January 24, 2016, 10:35:04 pm
content: Good Morning All,Got some batteries made for some in house systems but before we purchase more I need to do some testing on them to make sure they are the specs we need.We don't have the correct equipment to do the testing with so I am wondering if anyone knows of someone that we could pay to do the testing on the battery.It is really just testing of the discharge to make sure that the capacity of the batteries are what we asked for.Thanks

author: mojoe
author_rank: Frequent Contributor
timestamp: January 25, 2016, 05:43:47 pm
content: I can't recommend anyone, but it is easy to do it yourself. One way is this:http://www.westmountainradio.com/product_info.php?products_id=cba4(I have one).Or, get one of those Maynuo (sp?) load testers mentioned on the forum.

author: PTR_1275
author_rank: Frequent Contributor
timestamp: January 26, 2016, 02:34:05 am
content: +1 for the West Mountain Radio units, I have one and use it a lot.Where a bouts are you located? I am in Western Australia and if you only need to do a few verification tests I can put it on my CBA4
Battery testing using an Agilent 6632B - Page 1
Forum section: electronics / projects

author: hazzer
author_rank: Regular Contributor
timestamp: January 27, 2016, 03:24:41 pm
content: Hello - here's a video describing some excel battery test software using the Agilent 6632B power supply as an electronic load. The Agilent 6632B will sink current up to its max capacity of 5amps, and this current can be controlled using the normal GPIB / RS232 commands as for current delivered to a load.The software runs inside excel, and is written in VBA, your welcome to use it or alter it to you own needs - its is offered with no warranty and on the understanding that it is experimental code and may on occasion behave in unexpected ways.Harryhttps://youtu.be/k347CpAq10sYou can download the code from here:https://www.dropbox.com/s/al55428qpgyk7lz/6632B%20battery%20testing%20ver19.xlsm?dl=0

author: gslick
author_rank: Frequent Contributor
timestamp: January 29, 2016, 06:04:07 pm
content: I just received a couple of 6632B power supplies yesterday. I haven't checked them out and verified their operational condition yet. I'll have to take a look at trying out your code when I get a chance to get things set up. I suppose programming in VBA might be more popular if the software was free. I don't currently have Excel/Office installed on my GPIB controller system.Did you look at the Keysight Technologies Battery Testing Application Note 5952-4191 ?http://literature.cdn.keysight.com/litweb/pdf/5952-4191.pdf

author: hazzer
author_rank: Regular Contributor
timestamp: January 30, 2016, 02:47:48 pm
content: Yes Excel is not exactly free, Microsoft did at one time offer the "office 2007 pack" for $10 with their Enterprise Agreement so employees could use it at home, but that was a few yrs back.The application note talks about a one off measurement of output resistance - but I was keen to see how it changed over the discharge cycle, hence the continuous measurement. The code could be changed to make a test more in keeping with the Agilent app note, but I just wanted to be able to compare cells from different suppliers, so the relative difference was what I was really after and over the whole discharge cycle.The 6632 is a robust supply - I'm sure the units you have will be fine.H
Batteryless sensor node with RF energy harvesting and super cap - Page 1
Forum section: electronics / projects

author: Nikos A.
author_rank: Regular Contributor
timestamp: May 24, 2023, 07:23:05 am
content: Hi everyone,We are currently working on a concept for designing a batteryless sensor node. The node will be equipped with the Powercast P2110B Powerharvesterhttps://eu.mouser.com/datasheet/2/329/P2110B_Datasheet_Rev_3-3159474.pdfand a supercapacitor a sensor and low power MCU. Additionally, we have the P2110 evaluation boardhttps://eu.mouser.com/datasheet/2/329/P2110_EVB_Rev_C_instructions_rev_1-3159512.pdfand the TX91501 transmitterhttps://www.mouser.com/datasheet/2/329/User-Manual-TX-915-01-Rev-A-4-1511111.pdfto assist with the development. It's worth noting that I have never integrated a supercapacitor into my designs before.I have a few questions:On the evaluation board, can I exclusively use the supercapacitor to power up the sensor node, considering that the node will be designed to operate at ultra-low power? Or it should be combined with a battery?I've noticed that the supercapacitor discharges very quickly, even when I have disconnected the loads (S2 of the evaluation board). Is this normal behavior for such a small supercapacitor?In the timing diagram of the Powercast P2110B Powerharvester (page 3), it states that Vout (load supply) will be high when Vcap is 1.25V and will be set to low when Vcap is 1.02V. Doesn't this leave very little room for operation? Also, does the Vmax=1.25V limit the energy stored in the supercapacitor (E = 0.5CV^2)?On page 4, there is an equation provided for calculating the minimum required capacitor based on the load and the time of operation: C = 15 * Vout * Iout * ton. I'm having trouble understanding this formula. Based on my knowledge, shouldn't the minimum required capacitor be calculated as C = (I * t) / ΔV, where ΔV represents the allowable voltage drop across the supercapacitor?Thank you in advance for your assistance.

author: Nikos A.
author_rank: Regular Contributor
timestamp: May 26, 2023, 06:43:47 am
content: Anyone?
Batterypole corrosion - Page 1
Forum section: electronics / projects

author: somlioy
author_rank: Regular Contributor
timestamp: December 10, 2013, 04:21:22 pm
content: Was checking some batteries on an UPS today at work and came over a pair that had some corrosion on their poles. What exactly is causing this?Edit:Also, is it only me or does the Message-Field not appear in chrome?

author: SeanB
author_rank: Super Contributor
timestamp: December 10, 2013, 05:09:11 pm
content: Cracked top cell seal where the terminal goes through that allows the acid vapour to leak through and corrode the terminal. Clean off with baking soda and replace the bus bar and the nuts and washers. With the new ones use a dielectric grease liberally around them and the area of the cell seal. Otherwise replace the 2 affected cells and wash the rest down with baking soda and when dry give them all a dielectric grease coat.

author: AndersAnd
author_rank: Frequent Contributor
timestamp: December 11, 2013, 10:44:25 am
content: http://www.cartalk.com/content/today-why-buildup-you-cars-battery-posts-could-be-sign-something-seriousQuote

author: edpalmer42
author_rank: Super Contributor
timestamp: December 11, 2013, 05:32:10 pm
content: Is that a crack across the round part of the right-hand corroded terminal? If so, that cell is scrap and should be replaced ASAP. You won't be able to seal it and it might not be safe to use. If the power fails you could pull significant current through that cracked connector. Lots of bad things could happen.Ed

author: TheBay
author_rank: Unknown
timestamp: December 12, 2013, 12:18:07 am
content: I use petroleum jelly on cars...However something is not right there, what brand UPS is it, what reading is it giving with a mutimeter during charge and float? I know a fair bit about APC units if it's one of them.

author: calexanian
author_rank: Super Contributor
timestamp: December 12, 2013, 06:56:34 am
content: That unit has taken a good jolt and twisted that seal and the adjoining battery. The batteries are toast....

author: TheBay
author_rank: Unknown
timestamp: December 12, 2013, 02:19:57 pm
content: I wouldn't replace just the damaged cells, I would replace all. But please test charge and float with a meter first before blowing money on new batteries.
Bat/Ultrasonic Sound Detector/Converter - Page 1
Forum section: electronics / projects

author: brue
author_rank: Contributor
timestamp: March 06, 2012, 10:58:03 pm
content: HiIm looking for a circuit of an "Bat Detector" who can convert ultrasonic sound in herable frequencies. We want to use it for our rats, they produce ultrasonic sounds as well. (20-200kHz)I would prefer a circuit without a bandwith selector. Just convert the whole 20-100 kHz to hearable. Knows anyone a circuit?Thanks

author: vk6zgo
author_rank: Super Contributor
timestamp: March 07, 2012, 04:18:15 am
content: Unless you have an 80kHz hearing span,you will have to separate the spectrum into useable portions,somehow.It all depends on what you intend to use it for,If it is just to detect the presence of the rats,you could find out the dominant spectra in their "speech",make a device tuned to the middle of that frequency range,& then convert this narrower band of frequencies into the audible spectrum.If rats are anything like humans,their 'speech" is in two parts,--the lower frequency part forms the utterances into 'words" & the high frequency part gives it its character.If you wish to hear all of this span you are stuck with using some form of tuning.You could collect the sound with a wideband microphone,feed it into a mixer,the local oscillator of which is located within the frequency region of interest,then feed the resultant difference frequencies into your sound card.There are several different versions of software which could give you a spectral display of this resultant range of frequencies-----Hams use them for Software Defined Radios (SDR).The software allows you to "tune" to particular frequencies in this passband,using your mouse.Of course,to cover the whole spectrum,you would need multiple crystal oscillators.If you don't mind mixing them all up,you could use one oscillator with a lot of harmonics,but the result would not be very useful.

author: T4P
author_rank: Super Contributor
timestamp: March 07, 2012, 12:41:00 pm
content: 20-100khz hearable , use a octave down ?

author: saturation
author_rank: Super Contributor
timestamp: March 07, 2012, 12:54:26 pm
content: This is a favorite project easily googled:http://pw1.netcom.com/~t-rex/http://www.micro-examples.com/public/microex-navig/doc/077-picobathttp://www.batmanagement.com/Ordering/acoustic/hardware.htmlJust a few among so many.

author: sacherjj
author_rank: Frequent Contributor
timestamp: March 07, 2012, 01:54:04 pm
content: This was also in Nuts and Volts Magazine June 2011. It was a fairly simple OP Amp based circuit.
FTDI C232HD-DDHSP-0 cable: BaudRate altered when Enable Selective Suspend ticked - Page 1
Forum section: electronics / projects

author: brumbarchris
author_rank: Regular Contributor
timestamp: February 23, 2024, 10:08:31 am
content: Hello everyone,I am using a recently purchasedFTDI C232HD-DDHSP-0cable. I need to use it with on aWin10based PC, at acustom baudrate of 1843200 Bps, 8 data bits, 1 Stop bit, with theEnabled Selective Suspendoption activated:Nevertheless, it looks likethe baud rate is affectedby setting this option in the Settings for the COM port of the Windows 10. You may see below an oscilloscope screenshot depicting some bytes sent via the FTDI cable over the UART to the device we have connected to the cable. The screenshot depicts the same message being sent over the UART from the FTDI cable with theEnable Selective suspendoption beingtickedand the same message sent with this option beingun-ticked. In both cases, the displayed message is sent 5 seconds after opening the COM port with the PC software, so even in the case with Enable Selective suspend being ticked there is enough time for the FTDI cable to go out of suspend before sending the message.- On channel C1 (yellow): Enabled Selective Suspend option isun-ticked(which is the default) and the FTDI cable works correctly and as expected (our device connected to the cable receives and correctly interprets the message sent from the PC via the FTDI cable). In this case, the duration of a byte transmitted (including the start and stop bits) is5.425us, which isexactlythe expected value corresponding to the configured baudrate of1843200 Bps- On channel R1 (grey): Enabled Selective Suspend option istickedand the FTDI cabledoes not work correctly(our device connected to the cable does not understand the message sent from the PC via the FTDI cable). In this case, the duration of a byte transmitted (including the start and stop bits) decreased to5.013us, which is quitefar away from the expected value of 5.425us; it is then understandable that the message is not understood by our device connected to the cable.The only difference in the two cases is the Enable Selective suspend option beingtickedorun-ticked.Maybe one other relevant point is that the default configuration of the FTDI cable was initially changed via the FT_Prog so thatUSB Remote Wakeupis disabled andPull Down IO Pins in USB Suspendis enabled (see attachedEEPROM configuration.txt). These changes are intended and they are valid throughout both the working and the unworking situations described above.Other relevant information:- Operating system: Windows 10 Enterprise, 10.01.19045 Build 19045- VCP driver version: 2.12.36.4Is there is something you suspect I am doing wrong, or if this a known problem of the FT232H on which this cable is based on?Best regards,Cristian
BC²: Back-current circuit  - Page 1
Forum section: electronics / projects

author: abebarker
author_rank: Contributor
timestamp: June 15, 2015, 08:56:34 pm
content: Here is a neat little circuit I think you may appreciate. I ran across this while researching MPPT controllers. It can be configured for a boost or a buck topology. It uses an additional transformer and diodes to reduce transistor switching losses when hard switching a current (transitioning from a low to a high resistance while current is flowing). It also has energy recovery features (like a snubber).This circuit may be patented but I'm not worried about that for personal use.YouTube presentation;Novel energy-recovery circuit (ePresentation)I couldn't find this PDF on ST's web site any more but I'll share it here;AN3276 ST solution for efficiency improvement in PFC applications, back current circuit (BC2)https://www.dropbox.com/s/gcvbuz3u8jlv2l3/AN3276_ST_solution_for_efficiency_improvement_in_PFC_applications%2C_back_current_circuit_%28BC%C2%B2%29_1.0.pdf?dl=0

author: T3sl4co1l
author_rank: Super Contributor
timestamp: June 16, 2015, 05:41:25 am
content: Laughably useless: the analysis makes no mention of coupling coefficients, and seems to assume the "secondary" inductors are perfectly coupled and have zero inductance! Their poorly visible schematic, later, seems to suggest all four inductors are coupled, with no mention of magnitude or ratio.Dual-winding inductors are damned hard to come by, too. Let alone multiple. This will only ever be a full-custom or look-at-our-dev-kit-won't-you-please kind of thing.Resonant (or quasi-) snubbers are a related subject, and never really get all that much traction, either. Analyses are typically oversimplified, and wholly miss the disadvantages of the circuits: excessive peak current (during switch-on) and peak voltage (during switch-off), each often double the normal magnitude (thus the switching device needs quadruple the switching capacity); time taken for commutation (restricts PWM or frequency range); and the actual necessity of losses (powdered iron inductors are typically required, to dampen the energy lost due to reverse recovery and parasitic capacitance; the Q factor therefore can never be much over 10).Resonant supplies (usually LLC network, half or full bridge inverter) seem to be much better. Though you pay the price in switching current (maintaining reactive current at all times), voltage is strictly clamped, and switching itself can be clean and consistent. The main price paid is control: usually, frequency modulation is used, which has a very non-LTI response with a resonant tank's amplitude. Which partly depends upon having a very low Q (under 5), so that the control is fairly damped, making things easier to deal with.Tim
BC807 without a base connection? - Page 1
Forum section: electronics / projects

author: jwhitmore
author_rank: Regular Contributor
timestamp: July 27, 2017, 08:06:12 pm
content: I'm looking at using a smart FET, in a project and was looking at the Infineon BTS5045-1EJA. In the datasheet  (Pg 49) is an example circuit for using the device. In that circuit there's a transistor, a BC807, which has no base connection. I did a search on the Internet as I'm a bit confused by this circuit and all I could find was a stackexchange question . Unfortunately there didn't seem to be a conclusive answer to the question asked there. Some people suggested that you'd fry the device. The Infineon datasheet  states that the BC807 is to protect against reverse polarity. Now I have seen a nice circuit to protect against reverse polarity featuring a P-FET which has a very low forward voltage drop, compared to a protective Diode, but that circuit did connect all three pins.There are too many circuits! Any chance somebody could explain that small part of the circuit? I'd be really grateful.http://www.farnell.com/datasheets/2211532.pdfhttps://electronics.stackexchange.com/questions/98066/how-does-this-bjt-transistor-work-without-any-connection-to-its-base?rq=1

author: T3sl4co1l
author_rank: Super Contributor
timestamp: July 27, 2017, 08:14:28 pm
content: The circuit is "very simplified". Presumably, the transistor would be driven by control logic that decides when to connect R_OL and other things.Also, nowhere in that datasheet does it say "BC807"...Tim

author: MK14
author_rank: Super Contributor
timestamp: July 27, 2017, 08:17:55 pm
content: Quote from: T3sl4co1l on July 27, 2017, 08:14:28 pmhttp://www.farnell.com/datasheets/2211532.pdfExtract from datasheet:Quote

author: T3sl4co1l
author_rank: Super Contributor
timestamp: July 27, 2017, 08:41:35 pm
content: Oh, with a space. What the heck, that's not even a correct part number...Tim

author: MK14
author_rank: Super Contributor
timestamp: July 27, 2017, 09:00:21 pm
content: Quote from: T3sl4co1l on July 27, 2017, 08:41:35 pmI agree. They seem to have accidentally put the space in.As you said in your earlier post, it seems to be a very generic/approximate circuit, and NOT meant to be used directly as the actual circuit. Hence the base connection appearing open.They probably should have made it clearer, that something would be driving the base.

author: Ian.M
author_rank: Super Contributor
timestamp: July 27, 2017, 09:11:03 pm
content: Also see section 7.3.3.2 Open Load in OFF Diagnostic (page 31) which clarifies the use of a switched supply to ROL, i.e by controlling T1 by a level shifter from your MCU to enable polled OFF state open load detection.

author: jwhitmore
author_rank: Regular Contributor
timestamp: July 28, 2017, 08:07:35 am
content: Thanks for all that. I took it too literally I guess.
BCD Complement switch project ideas? - Page 1
Forum section: electronics / projects

author: rpetitho
author_rank: Contributor
timestamp: November 11, 2019, 05:31:12 pm
content: All I ended up with 12 of these. All are 0-9 BCD complement. Any project ideas?-Bob

author: SeoulBigChris
author_rank: Regular Contributor
timestamp: November 12, 2019, 11:04:58 am
content: Back in the early 90s I designed a digital frequency synthesizer add-on to an existing product. The user could dial in frequency using thumbwheel switches almost identical to these. This system didn't have a computer, and I ended up converting the BCD digits to the binary control word needed by the synthesizer using a series of EEPROMs - one bank to do BCD to decimal, and another to do a reciprocal operation.As for projects, how about using them to set a clock? Or build an old-fashioned front panel to a modern ARM embedded board.-Chris

author: Yansi
author_rank: Super Contributor
timestamp: November 12, 2019, 11:49:22 am
content: There are some interesting ICs for binary/BCD conversion, just as this one:http://www.utm.edu/staff/leeb/DM74185.pdf

author: shved
author_rank: Regular Contributor
timestamp: December 17, 2019, 05:07:02 pm
content: You can use it with 74ls42 or similar BCD chip.
BD9870FPS Buck switcher: Thermal resistance not stated --> no heatsink needed? - Page 1
Forum section: electronics / projects

author: 741
author_rank: Frequent Contributor
timestamp: December 16, 2019, 03:31:27 pm
content: I'm looking for an IC to step dowm from 24V to 5V, 150mA.The ROHM BD9870FPShttp://rohmfs.rohm.com/en/products/databook/datasheet/ic/power/switching_regulator/bd9870fps-e.pdfhas no mention of "thermal resistance". All I can find is "Power Dissipation" = 0.8W. (Some ambient temperature derating is given).Does that mean that its Rja (junction to air thermal resistance) is low enough that the device can simply be mounted on normal sized pads? That would be good news as it means prototying is easier.Even so, it might not be appropriate as it becomes very inefficient under about 200mA output.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 16, 2019, 07:54:05 pm
content: I've got a LMR14203 here, that doesn't seem to care, i.e. it doesn't get hot at similar loads.5V 200mA is only 1Wtotal output, how inefficient were you expecting it to be?Bigger pads and inner layers are always welcome, thermally speaking. Leave thermal spokes in for solderability.Tim

author: 741
author_rank: Frequent Contributor
timestamp: December 17, 2019, 09:51:27 am
content: Thank you, having an actual tried-out part number is ideal. I had a figure of 85% efficiency in mind. The curve for the 9870 is attached. I should have looked at lower power parts.
beach 40 xtals - Page 1
Forum section: electronics / projects

author: christopher iles
author_rank: Regular Contributor
timestamp: December 21, 2013, 05:52:59 pm
content: I have some 7.2MHz crystals if anyone is interested. £2.95 each.

author: Hideki
author_rank: Frequent Contributor
timestamp: December 21, 2013, 08:21:23 pm
content: You should probably get this moved to the Buy/Sell/Wanted forum.7.2 MHz is an odd frequency. Where is it commonly used? QRP radios?

author: christopher iles
author_rank: Regular Contributor
timestamp: December 22, 2013, 04:39:28 am
content: Yes, used in QRP radios (40m VXO).
Beam currents of analog scopes - Page 1
Forum section: electronics / projects

author: quak
author_rank: Newbie
timestamp: April 10, 2019, 09:58:23 am
content: I'm considering to use an analog scope as electron beam source for a physics experiment (as focusing optics and deflection are already included).I know the question how to cut a hole in the phosphor screen without destroying the CRT is an issue... for now I'm searching for a scope which can deliver >100 uAmps beam current which can be deflected with frequencies >100 MHz.We measured that the Tektronix 2465 only delivers 20-40 uA, as far as I found out this is due to a mesh inside the CRT. There are several older CRTs (like the T503) which can reach this current according to their datasheet. Now the scopes equipped with those CRTs usually offer rather low deflection frequencies (up to 50 MHz).Does anyone know some scope with rather high beam current and frequency bandwidth from any manufacturer?Thank's for your advice!

author: dzseki
author_rank: Frequent Contributor
timestamp: April 10, 2019, 10:13:47 am
content: I think you mean the expansion mesh: that was invented in the 60's and all the high frequency oscilloscope tubes had that since then, because it ease the need of the high voltage post acceleration voltage.What you should consider is Tektronix's MCP (Micro Channel Plate) tubes, that can be found in the 2467 or the 7104. This was really state of the art construction with built in photo multiplier to the tube, although it would be sad to see destroying such a tube...

author: StillTrying
author_rank: Super Contributor
timestamp: April 10, 2019, 12:08:22 pm
content: With the tube held face down you could probably pull out nearly all of the mesh, it's very delicate. But then you'd need higher deflection voltages.https://entertaininghacks.wordpress.com/2016/03/09/rescuing-a-broken-tektronix-465-crt/#more-752
Beamer Hushbox - Fan control - Page 1
Forum section: electronics / projects

author: Rebius
author_rank: Newbie
timestamp: February 20, 2020, 08:28:28 am
content: Hi. I'm building a hushbox for my beamer and want to control my fans without any extra switches or knobs.My idea was to switch on the beamer and this would also switch on the fans, as they are decently quiet. I found a master-slave switch, but only one, and that one is switching on at about 40mA, but the beamer is taking 55mA in stand-by. I couldn't find any other switch with higher trip-point, or some adjustable one. And building my own master-slave switch is a project on its own. So my question(s):1) is there some master-slave switch for stand-by devices?2) is there some other plan (with parts list) that wouldn't take too long to build?3) is there another way to do this (f.ex. current sensors, thermostat, etc...)Thanks for all feedback
Beat Timing Circuit for LED Flasher - Page 1
Forum section: electronics / projects

author: CaptnYellowShirt
author_rank: Frequent Contributor
timestamp: June 01, 2014, 07:45:26 pm
content: I'd like to build a low power circuit that can flash a high-power LED to a specific beat. The beat goes three long-spaced flashes followed by three short-spaced flashes -- perhaps akin to Morse Coding out "O" and then "S".The flasher would ideally pause for a long period of time (three to four times the length of the beat) and then repeat indefinitely.My first idea is to use a microcontroller. But I wanted to source an idea or two here before getting started. Thanks.

author: Paul Price
author_rank: Super Contributor
timestamp: June 02, 2014, 02:37:12 am
content: You could accomplish this with too many parts and 555 timers, so why not go for MCU?You can do whatcha want with too many (a few) LM555 oscillators and a few small diodes to steer logic for control, maybe a few resistors, or pots, a few capacitors and maybe a transistor or two and a CD017 may be needed to do the job with some class.The first 555 generates the short beat and the second 555 has a period equal to the time for the three fast beets and connects to the V/C input of the first 555 to extend the beat (period of the output) for only a time that corresponds to the three short beats. The third 555 has the longest period and blanks the first two 555's for the inter-beat muted pause by holding them at reset. Add more 555's to create your own state machine to generate any other subtle pause/active 555 timing effects.An other way:A 555 can feed the clock input to a CD4017 that has sequentially enables only one output at a time and is reset by a diode on the last output timing period output(this connected to the reset input. Then each output "state" controls the enable/ timing of 555 timer's for the beats. The 4017 counter becomes a sequencer functioning as a "state machine."Or something like that.

author: CaptnYellowShirt
author_rank: Frequent Contributor
timestamp: June 02, 2014, 04:00:24 am
content: The state machine idea occurred to me too... but I had no idea how I'd implement it. The MCU seemed like the best option from the start but I wanted to check in with the people who know more about this stuff than I do.

author: Paul Price
author_rank: Super Contributor
timestamp: June 02, 2014, 06:11:30 am
content: The Microchip 16F716 cost about $1, has 128bytes of R/W RAM and 2Kx14Words Flash Mem, easy to program this task in C in just a few lines of code. PWM can even vary brightness depending on a light sensor connected to an A2D input, and a dip Sw. or jumpers can set umpteen blink code options, but why geld your RAM?
Because who needs SMPS chips anyways - Page 1
Forum section: electronics / projects

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 23, 2014, 08:06:45 pm
content: I like to play with discrete switching circuits from time to time. This one uses ten active devices, and performs as well as a UC3843, with variable frequency action added in:The quiescent current isn't as good, and the low voltage startup, and short circuit tolerance, leave something to be desired, so it's not quite ideal. The operation (in terms of waveforms) and efficiency are pretty nice though.Of course, I do like the dirty trick of using a TL431 (in essence, a glorified BJT with 2.50V Vbe and huge gain) while counting it as only one active device.Tim

author: calexanian
author_rank: Super Contributor
timestamp: January 24, 2014, 04:22:41 am
content: I take it this is for a tube preamp or something. why switch for your filament voltage? Just use your 12 volts.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 24, 2014, 02:54:07 pm
content: Yes, though I've made similar circuits for various purposes (24V, +5V, -12V, etc.). Obviously, a given output is just a winding away.Reason for this was, I was breadboarding odd numbers of 6.3V tubes. Lot of hassle matching resistors every time I pull or add one. Much better to just have 6.3 to begin with.Tim

author: calexanian
author_rank: Super Contributor
timestamp: January 24, 2014, 03:38:15 pm
content: Why not use either two tubes of the same filament current in series or 12 volt tubes? 12ax7 etc....
BECKMAN TECH 360 schematic circuit diagram - Page 1
Forum section: electronics / projects

author: Voxman
author_rank: Contributor
timestamp: July 08, 2021, 04:07:59 pm
content: Hello Everyone,I’m trying to install an LED power indicator on my Beckman 360 multimeter.My problem is the power switch that turns meter on and off doesn’t receive the 9 vdc battery voltage.When I measure the voltage on the switch, it is about 7.58vdc. So I assume it’s because the switch isconfigured differently that an ordinary power switch. The switch itself has 5 terminals that have NO voltage on any of the terminals until it’s powered on.I need a schematic to figure out why and where I can tap into the 9vdc that is switched.Any help is appreciated!ThanksVoxman

author: floobydust
author_rank: Super Contributor
timestamp: July 09, 2021, 06:39:33 pm
content: The on/off switch opens the battery pack (-) to GND, which might be confusing.The multimeter IC has a 6.5V regulator which powers everything except the Ohms source gets raw 9V.I haven't seen a Beckman service manual on the web, I used to have a paper one but would have to dig for it.The TECH 350/TECH 360 Owner's Manual has a tiny partial schematic.Battery lifetime is rated 12,000hrs so adding an LED seems unusual.

author: Voxman
author_rank: Contributor
timestamp: July 15, 2021, 06:06:42 pm
content: Floobydust,Thanks for posting the info. I went ahead and tapped into the switch voltage and it is working fine on a prewired, normally 12vdc powered LED. There isn’t much room to install a LED but did find a space.As far as the current drain on the 6 D size batteries, you’re absolutely right that is almost inconsequential but I have a bad habit of leaving it on accidentally for days on end. The LED will alert me if I leave it on…BTW I love this meter…it has been such a dependable and accurate meter for almost 40 years now!Thanks anyway for the info…appreciate the reply.Voxman

author: floobydust
author_rank: Super Contributor
timestamp: July 15, 2021, 07:00:43 pm
content: I have scanned the Beckman Tech 350/Tech 360 manual but the page size is terrible, really wide and narrow. Next is to get my buddy with Acrobat to put it in a single pdf. Otherwise I couldn't find it on the web. I'll PM once finished.I've got a Tech 360 to repair, one 10uF blue electrolytic capacitor getting bad leaked a bit after 40 years and LCD a bit wonky. Might be worth it to retrofit an Eneloop AAA 9V pack for it.

author: blacksand
author_rank: Newbie
timestamp: April 23, 2023, 03:53:55 pm
content: Would also like a copy of the schematic for Beckman 360 please. Can you post a link or pm a copy.Dan

author: floobydust
author_rank: Super Contributor
timestamp: April 24, 2023, 01:10:45 am
content: This is the Tech 360 schematic scan I have from the tiny owner's manual booklet. The original print resolution was a bit low.Also a pic of an eBay listing page for the service manual but somebody scooped it up before meIt shows Beckman Tech 350, Tech 360, Model 3050, Model 3060 bench multimeters PCB layout.