hybridfree/eevblog-posts huggingface dataset:
Charging a supercap from a boost converter - help! - Page 1
Forum section: electronics / projects

author: Pete_UK
author_rank: Contributor
timestamp: March 07, 2023, 04:27:31 pm
content: I'm having a hard time trying to find any examples of charging a supercap from a boost converter architecture. I need to be able to charge a few farads of supercap to 20V, from a battery power source which is nominally 6V, so I was looking at using a boost converter running in constant-current, with some means of then shutting off when the required voltage is reached. In this application one side of the supercap is permanently wired to ground, so this will necessitate high-side current sensing. The charging current is relatively low, at around 100mA. I've had a play around in LTspice with some regular LT boost converters, and unfortunately it all starts to get a bit messy right away, eg. the high-side sensing requirement makes it difficult to derive the feedback, which then initially massively over-shoots due to the boost topology etc. If anyone has done something similar, or has any advice on parts or better suited topologies (eg. buck-boost, or SEPIC?) then that would be great to hear about. Thanks!

author: SuzyC
author_rank: Frequent Contributor
timestamp: March 07, 2023, 08:30:47 pm
content: Do post a schematic. From what you describe, you've seemed to found an elegant but over complicated solution to your design problem.Post your charging power source voltage its current capacity.What are your requirements about the footprint and also efficiency and current accuracy you need for boosted V CC charging?Do you have room for a small heat sink for a power transistor that would be the constant current source?There could be an easy solution, a quick and dirty solution.

author: langwadt
author_rank: Super Contributor
timestamp: March 07, 2023, 08:48:58 pm
content: Since a boost has an inductor and diode directly from input to output it can't limit the current when the output is less than the inputyou'd need something like a sepic, but then something similar to this current limit for a buck might work

author: SuzyC
author_rank: Frequent Contributor
timestamp: March 07, 2023, 10:28:57 pm
content: A boost converter raises the voltage to the proper level. A single transistor configured as a constant current generator then sets the charging current.

author: lastguy
author_rank: Contributor
timestamp: March 08, 2023, 11:16:00 pm
content: your idea is too far for such design.

author: Pete_UK
author_rank: Contributor
timestamp: March 10, 2023, 12:18:06 pm
content: Thanks all for the replies, and thanks langwadt for the schematic idea (looks quite useful). I agree that it looks like Buck-Boost or SEPIC is probably the best way to tackle the problem. I'll try out some more ideas in LTspice & report back later how it works out..
Charging a SuperCap with a linear regulator - Page 1
Forum section: electronics / projects

author: Jester
author_rank: Frequent Contributor
timestamp: November 25, 2020, 04:13:54 pm
content: Does anyone have experience charging a Supercap with a linear regulator?I don't have the luxury of adding a current limiting circuit as I will be simply connecting the SC in parallel with the output of the regulator (MIC39100-5.0WS) on an already existing circuit. I would imagine the regulator will simply current limit for the 10s or so it will take to charge. Not sure about the regulator being energized on the output with no input, the datasheet talks vaguely about reverse current protection.https://www.digikey.ca/en/products/detail/FYH0H474ZF/399-17224-ND/8565910?itemSeq=346077208https://www.digikey.ca/en/products/detail/microchip-technology/MIC39100-5-0WS/771642

author: coromonadalix
author_rank: Super Contributor
timestamp: November 25, 2020, 06:22:17 pm
content: tried with an 3.3 farad super cap, took 15 minutes to charge at 2 ampsbut with an bms, cause i used an linear regulator, and when i put the super cap, its like a short for a few secs, it was going into overload ...As the spec sheets it depends if you use it like a battery or a capacitor, it could take a few secs or hours to charge ?
Charging laptop off Solar - Page 1
Forum section: electronics / projects

author: shadow_mist1
author_rank: Newbie
timestamp: May 20, 2021, 11:12:08 pm
content: Hello, I'm thinking about charging my laptop off some solar panels connected to a 12V battery and I was wondering if anyone has any ideas on how to do that without using a 12V to 240V inverter to use my regular charger. Is there a more efficient way to up it to 19.5V?

author: NiHaoMike
author_rank: Super Contributor
timestamp: May 20, 2021, 11:41:18 pm
content: Use a boost converter.

author: tunk
author_rank: Super Contributor
timestamp: May 21, 2021, 10:58:22 am
content: Something like this?https://www.ebay.com/itm/402682228893?hash=item5dc1bb309d:g:ACsAAOSwAfVbuwdSDon't know about quality or seller (cheapest one searching for "laptop 12v car").

author: amishasingh
author_rank: Contributor
timestamp: May 21, 2021, 11:42:21 am
content: If you are implementing it in the real time ensure to have the quality and proper components. Because sometimes it leads to hit the performance of your laptop battery
Charging LED  - Page 1
Forum section: electronics / projects

author: drummerdimitri
author_rank: Frequent Contributor
timestamp: October 15, 2020, 02:28:58 pm
content: I have an old electronic screwdriver that I've recently converter from Ni–Cd to a Li-Ion battery and had to rewire the internals as well as de-populate the internal charging PCB to accommodate an external Li-Ion charger.While doing so, I realized that the original charging LED that only lit up when the tool was docked and charging now lights up even when it is not charging and with time, eventually drains the battery flat.I've already used a diode to drop the voltage that reaches the red LED to around 2.7 V on a fully charged (4.2 V) battery however, I'm not sure how I should add another diode to make it only light up when the tool is charging.Surely this is an easy fix but I don't have any experience with this.

author: drummerdimitri
author_rank: Frequent Contributor
timestamp: October 18, 2020, 12:56:45 pm
content: BUMP!

author: MarkF
author_rank: Super Contributor
timestamp: October 18, 2020, 01:13:16 pm
content: Manufacturer? Model? Picture? Schematic?Help us... help you...
Charging LifePO4 battery with CC power supply? - Page 1
Forum section: electronics / projects

author: drummerdimitri
author_rank: Frequent Contributor
timestamp: November 26, 2021, 02:18:18 pm
content: Would it be possible to use a Constant Current DC power supply with an adjustable output voltage to charge a 12V LifePO4 battery with a capacity of 120 Ah?It is my understanding that these cells should be charged via CC and then CV which is exactly what this power supply would be doing with a max charge rate of 60A or (0.5C) and can be set to a maximum of 13.6V (99% SOC for this battery).Should I try doing this or should I invest in a dedicated 2 or 3 stage battery charger? I will be using it to power a 1200W pure sinewave inverter with a bypass function when AC power is present as it does not come with an integrated battery charger.Seems safe to me but I would like to hear from people with more experience.

author: drummerdimitri
author_rank: Frequent Contributor
timestamp: November 29, 2021, 11:14:19 pm
content: BUMP!

author: thm_w
author_rank: Super Contributor
timestamp: November 30, 2021, 11:10:51 pm
content: Yes it will work. May want to take precautions in case of backfeed, as it could destroy some PSUs.We are talking about a 12V battery with built in BMS in case of over/under temperature and voltage right?https://www.youtube.com/watch?v=-c6A1THDaeU(psu shown)https://www.youtube.com/user/errolprowse

author: drummerdimitri
author_rank: Frequent Contributor
timestamp: November 30, 2021, 11:34:39 pm
content: Quote from: thm_w on November 30, 2021, 11:10:51 pmYes exactly, the battery is a 12V (4s) configuration with an external BMS.I've actually gave this setup a try and it works brilliantly and no problems with backfeed as I initially purchased this PSU to charge my 12V supercapacitor bank from 0V.
Charging multiple devices with a simple 5V power supply - Page 1
Forum section: electronics / projects

author: Erwin Ried
author_rank: Regular Contributor
timestamp: September 29, 2019, 09:08:35 am
content: Hi! I want to charge several USB devices with a simple power supply (the usb devices connected in parallel to the supply and the D+ and D- can be shorted with a switch for tablets that assume that is 1.5A not 0.5A supply), should I have something (electric) in consideration?

author: mariush
author_rank: Super Contributor
timestamp: September 29, 2019, 11:07:29 am
content: It would work.Ideally, you would get some charging controller ICs that auto configure the data wires for you , going through multiple configurations of signals on those data wires and auto detecting the right way to get your device power at max speed.For example see TPS2514 (single) or TPS2513 (dual)TPS2514 :https://www.digikey.com/product-detail/en/texas-instruments/TPS2514DBVR/296-39376-1-ND/5143327TPS2513 :https://www.digikey.com/product-detail/en/texas-instruments/TPS2513ADBVR/296-39375-1-ND/5143326The footprints are the same, the TPS2514 simply doesn't have two pins connected to anything.They're surface mount, but should be fairly easy to solder by hand ... for example you could just bend the middle pins (input voltage and ground downwards) and the side pins (data+ and data- for each usb port) upwards to increase distance between pins and then you could simply solder thin wires to each lead.You can also get adapter boards :https://www.ebay.com/itm/SOT23-6-SOT457-Breakout-Board-Adapter-for-Prototyping/202474684418

author: Erwin Ried
author_rank: Regular Contributor
timestamp: September 29, 2019, 07:37:30 pm
content: Thanks! I though on using something like that but I took appart a lenovo usb supply and it just shorted them out 😂😂 but the v+ and gnd, they dont require diodes or anything? The supply I have is enough so I am thinking if something can happen between devices that needed my attention
Charging NiMh battery pack - Page 1
Forum section: electronics / projects

author: soldar
author_rank: Super Contributor
timestamp: May 02, 2024, 09:04:01 am
content: I have rebuilt a NiCd drill battery pack with NiMh cells and need to decide on how I am going to recharge it.After reading a bit on this topic I am inclined that the charger should have a faster charging, say C/5, a slower charging, say C/20, and then shut off, zero charging.I can push a button and start on low charge directly and the charger will shut off when the voltage reaches 22VI can push a different button and the charger will start on fast charge until it reaches 22 V and then it switches to slow charge until it again reaches 22 V and it switches off.This seems easy enough to implement with a very simple electronic circuit and I think it would be a good charging policy. If I am working with the drill I can fast charge. If I have finished for the day I can slow charge.I welcome comments and ideas.

author: mariush
author_rank: Super Contributor
timestamp: May 02, 2024, 09:46:14 am
content: I wouldn't have bothered... that's what ... 18 cells?Ideally, you would add some kind of fuel gauge IC to know how much energy is still left in the cells, and for example if the amount is below some threshold, run the cells down, discharge them, and only then charge them up.Not sure how I'd do it .. maybe I'd have the battery arranged in 3 groups of 6 cells, or 6 groups of 3 cells that could be charged in parallel (have some solid state relays or some way of separating the groups when you plug battery in charger)This way you'd be able to charge the groups with 5v (for the 3 cells in series) or 9v or higher for the groups of 6 cellsYou'd probably be better off with a pack of LifePo4 cells ... with 3.6v charge voltage, you could have 6 in series and charge them directly with a 20-21v power adapter (charge voltage would be up to 3.6v per cell, 6 cells x 3.6v = 21.6v ... charging them to lower maximum voltage will increase their life)
charging non-rechargable battery under a circuit failure, risk of fire? - Page 1
Forum section: electronics / projects

author: diegopm
author_rank: Newbie
timestamp: May 31, 2020, 10:21:23 am
content: Hi,I have a system that is powered by two redundant power supplies, 12V from a commercial adapter and 9V from a non-rechargeable battery. This is managed by an ORing circuit of Schottky diodes that has an inverse current of several uA depending of temperature.I have two questions:What happens to non-rechargeable battery if a small current pumped in (charging at several uA along the time)?What happens to non-rechargeable battery if my circuit has an unusual problem (short circuit, free cable touching parts, user manipulation, short circuit in ORing element, etc.) that put 12V to 9V battery for a long time?I am concerned about risk of fire or explosion if a high charge current is applied (as manufacturers says in datasheet). Or a liquid leakage if a tiny charge is applied due to inverse current of the diode.Thanks and best regards.

author: wizard69
author_rank: Super Contributor
timestamp: May 31, 2020, 04:17:39 pm
content: If you have a fear of circuit failure then it would make sense to me to fuse the circuit to the battery at the very least.As for batteries leaking if you are talking alkaline I really don't see anyway to positively prevent premature failure of these sorts of batteries. It has gotten so that I'm not even willing to buy such anymore due to all the damaged hardware i've had due to the infernal leakage.I actually thought I could out smart the leaking battery problem by running around and changing all batteries on my birthday every year. That didn't work! So now I look for solutions other than alkaline batteries.Now that that rant is over I have to wonder just what type of battery are you using? Some are more prone to fire than others. If this is a critical application it would probably be best to consult with the battery manufacture.

author: David Hess
author_rank: Super Contributor
timestamp: May 31, 2020, 05:54:14 pm
content: UL has requirements for this sort of thing. At low currents, nothing bad happens. Typically two diodes in series are required in case one shorts and a series resistor should be included with a value consistent with the expected current draw.
Charging SLA batteries with lab power supply. - Page 1
Forum section: electronics / projects

author: jeeves47
author_rank: Newbie
timestamp: July 17, 2017, 02:02:23 pm
content: I'm sorry if this has been covered before, but I am new to this and can't find what I want.I’m using an Instek 3030 Power Supply to charge SLA batteries including an 18-volt pack I made up to power a cordless chainsaw. I read that it was advisable to use a diode in series with the +output, so I am using a 1N5402. This gives a voltage drop of about 0.4-volts, and I have to use a DMM to get the right output. My question is whether the diode is really necessary.

author: mikerj
author_rank: Super Contributor
timestamp: July 17, 2017, 02:09:19 pm
content: Many bench supplies do not like voltages being applied to the output terminals when they are switched off, or if the output is set lower than the applied voltage. I have no idea if the Instek supply is in this category, but if it is you do risk damaging it it without the diode.

author: Siwastaja
author_rank: Super Contributor
timestamp: July 18, 2017, 04:22:40 pm
content: Proper lab power supplies are, of course, OK without any diodes like that.Some cheapies do blow up when you do this, but they are often completely unusable and totally broken-by-design beyond any repair even before that happens, so it's often a good thing to get completely rid of them. This being said, I've seen supplies that do not blow upcompletely, but end up being in an even more broken state than before, but appear still "working" to someone who doesn't test them thoroughly.Note that even if the supply is not damaged by reverse current flow, the battery might discharge through the diode if you turn off the power supply or adjust the voltage too low. If you forget it like that, an SLA is easily damaged due to sulfation.Of course, if you first turn on the supply, set the voltage to higher than the battery, then connect the battery, then remove the battery before switching off the supply there is no reverse current flow and thus, no need for a diode.
Charging Station PCB Design - Page 1
Forum section: electronics / projects

author: frog7227
author_rank: Newbie
timestamp: August 11, 2015, 04:21:10 am
content: Hello, I'm new to PCB design (and the forum for that matter) and I recently made my first PCB for a project I'm working on, because of this I'd like to know if the layout is good, or if/what ways I should tweak it. When designing it I ran into not having a component (Fairchild FQP30N06L N-Channel MOSFET in the TO-220 Package) in my library so I used a 7805 in the same package so I could just get it done. This board connects to a Rev. 2 Raspberry Pi Model B. The silkscreen's a mess, which I will work out, but I'd just like some comments on it.Thanks.I made it in Cadsoft Eagle (both the board and the schematic are in the .zip)SHA-1: 4778D9242F6E37F5BCD0062A7808D6D7B0BE520BMD5: C3D62EC47AE187B514A93F32E4D7835B(I used onlineMD5 to generate those so please notify me if they're not correct)
Charging status led for balance board? - Page 1
Forum section: electronics / projects

author: GadgetBoy
author_rank: Regular Contributor
timestamp: July 30, 2018, 03:04:51 am
content: So, I have a couple of super capacitor boards, and following Julian Ilett's instructions, I was able to add LEDs to the boards to indicate the charging status of each capacitor on the board.I'd like to do something similar to this 12v LiPo balance board I picked up, but the circuit is sufficiently complex that I'm not sure where to begin. I've attached a picture of the board in question.Any thoughts/advice?Sent from my ONEPLUS A3000 using Tapatalk
Charging times. - Page 1
Forum section: electronics / projects

author: davelectronic
author_rank: Frequent Contributor
timestamp: April 12, 2022, 02:15:56 pm
content: Times come for me to find a charging solution for a mobility scooter in a Lockup garage that has no power points. I've come up with two SLA batteries in parallel, powering an inverter and the scooter charger. My two SLA batteries are 12 Volts and 110Ah each, so I'm going to put them in parallel. The mobility scooter is powered by two 50 Ah batteries in series, so the scooter is a 24 Volt system. The part I'm struggling with is, as my journey times vary, I can't work out how long I need to charge from the inverter to scooter charger through the two SLA batteries. In recent times (emergency) I have charged the scooter via one SLA 12 Volts 110 Ah battery, this managed approximately 3 hours charge time via the inverter to scooter charger. I'm not asking for the numbers to work this out, more the formula to assume an average maximum charge time. The charger for the mobility scooter charges at 8 Amps, but drops to 4 amps as the charge nears completion. So once I've charge the mobility scooter through the SLA batteries, I then take the SLA batteries indoors to recharge the pair of parallel SLA batteries, ready for the next charge. Any help appreciated and thanks for reading.

author: madires
author_rank: Super Contributor
timestamp: April 12, 2022, 03:05:43 pm
content: That sounds like a quite inefficient solution. And the batteries need to be replaced every few years. Is it feasible to get mains power to the garage, to get a garage with power, or to install a small PV system?

author: davelectronic
author_rank: Frequent Contributor
timestamp: April 12, 2022, 06:28:03 pm
content: I agree it's inefficient, but I'm in a tower block, and my elevator is out of service for 3 months. There is no way I can get a power point installed, these are council community lock ups with no power in any of them. I will have to use the alternative elevator on the next floor down two flights of stairs. My Son is going to use a sack barrow (stair climbing varient) to get the two batteries down the stairs. I've tried to find another solution. But I'm out of ideas.
Charging your phone with USB 2.0 from PC - Page 1
Forum section: electronics / projects

author: tree
author_rank: Regular Contributor
timestamp: September 26, 2017, 09:33:15 pm
content: Hello folks,I've been pondering this lately and I'm sure there's someone here with experience in this field. So we know that the charging circuitry in modern smartphones charges the Li batteries inside with constant current up until some voltage and then switches to constant voltage charging. The problem I'm having is with the current limit on the USB 2.0 ports on your PC which are limited to 0.5A, 5V (2.5W). So suppose we're capable of charging our Lithium cells at 2A and our current battery voltage is 3.6V and we're charging in constant current mode. This means that we can supply ~ 7.2W. Assume it's 100% efficient.As you can see this presents problems. The input is limited in power. So how does the charging circuitry inside the phone KNOW how much power it can draw before the input supply droops?I hope this is clear...Thanks.

author: Howardlong
author_rank: Super Contributor
timestamp: September 26, 2017, 09:42:10 pm
content: The phone uses signalling of numerous different types to figure out the capabilities. USB-C introduces a more complex signalling protocol to allow for multiple voltages and currents.http://www.eetimes.com/document.asp?doc_id=1279469You can get chips to figure it out for you, for example the Microchip USB3751A series you can probe the capabilities at the device using I2C.

author: stmdude
author_rank: Frequent Contributor
timestamp: September 27, 2017, 06:03:06 am
content: Quote from: Howardlong on September 26, 2017, 09:42:10 pmYep, have worked on that particular part of cellphones, and you're quite right. We also did "foldback" detection, which means that we monitor VUSB, and if we see it dropping, we start pulling less current, as we're probably overloading the supply. This is needed to deal with crappy DCP implementations (aka, chinese chargers).We also backed off for a multitude of other reasons as well, mostly temperature-related.
charlieplexing on 10 led's - Page 1
Forum section: electronics / projects

author: gsingh11
author_rank: Contributor
timestamp: March 20, 2023, 05:14:24 pm
content: Hi, i am looking to control 10 leds from 4 pins of atmega328p. these leds are a kind of indicator. i am having a problem to arrange them in a single row for demonstration purposes. can anyone help me in how to arrange them in a row.

author: Terry Bites
author_rank: Super Contributor
timestamp: March 20, 2023, 06:43:22 pm
content: 4 bits gives you 16 binary states. A demultiplexer/ decoder is needed.Say a 74HC4514. It has active low outputs.A BCD decoder will do for 10 leds. eg a 7445, 74HC42, MC14028 etc.

author: jpanhalt
author_rank: Super Contributor
timestamp: March 20, 2023, 07:10:57 pm
content: For Charlieplexing, the formula for number of LEDs is n(n-1), where n = number of tristated control pins. Rather than go off on a tangent, can gsingh11 show the schematic he has developed? (See: Wikipedia)

author: Benta
author_rank: Super Contributor
timestamp: March 21, 2023, 10:53:04 pm
content: https://www.arrow.com/en/research-and-events/articles/charlieplexing-an-led-matrix

author: RES
author_rank: Regular Contributor
timestamp: March 22, 2023, 08:48:47 pm
content: check this link; 10 led charlieplexed bargraph:https://pic-in-pascal.blogspot.com/2017/06/led-bar-graph-charliemultiplexed.html

author: ali_asadzadeh
author_rank: Super Contributor
timestamp: March 22, 2023, 09:36:47 pm
content: Don't wast time and money like this, use MBI5043, it's supper cheap and has 16bit dimming for 16 LEDs, using only 4 pins to control, and you can cascade it for more LED's toohttps://www.lcsc.com/product-detail/LED-Display-Drivers_span-style-background-color-ff0-MBI-span-MBI5043GP-A_C110098.html

author: DavidAlfa
author_rank: Super Contributor
timestamp: March 23, 2023, 12:29:52 am
content: https://www.stuffandymakes.com/blog/2013/04/29/charlieplexing-leds-with-an-avr-atmega328http://www.multiwingspan.co.uk/arduino.php?page=vbcharlie

author: gsingh11
author_rank: Contributor
timestamp: March 29, 2023, 03:05:48 am
content: The problem is that i can do Charlieplexing and display leds but i need them to remain on as I light up others. In atmega its difficult to because I have to change the state of the pins every time i have to light a LED.

author: themadhippy
author_rank: Super Contributor
timestamp: March 29, 2023, 03:14:44 am
content: you need to run it faster so persistiance of vision gets a chance to play
Chassis mount USB to board - Page 1
Forum section: electronics / projects

author: HackedFridgeMagnet
author_rank: Super Contributor
timestamp: October 08, 2013, 06:59:56 am
content: HiI want to bring USB 2 type B(the pcb in the box is a slave so type B) from a panel/chassis mount connector mounted on a plastic enclosure, to a pcb within that enclosure.So that when I walk up to the box I can plug in my USB cable and down load my stuff and walk away.The panel connectors I am thinking of using are something likehttp://www.digikey.com.au/product-detail/en/MUSB-D111-31/MUSB-D111-31-ND/2567126orhttp://www.digikey.com.au/product-search/en?keywords=SAM8637-ND&stock=1I am not sure of the neatest way of getting it on board, if possible without having to make up specialised cables.The only way I can see doing it is to make up some sort of cable and put some header pins onto the pcb. Is there any conventions for this?I have used a flying lead in the past, but I am now wanting a panel mount.I don't mind B or miniB or micro B either.By the way I have heard that micro are better than mini but I have had disconnect troubles with the micro, due to loose tolerances, anyone else get this?

author: Richard_Fry
author_rank: Contributor
timestamp: October 08, 2013, 09:33:08 am
content: Hi,I've used those Samtec ones before (they're big at 2" diameter) and ended up just ended up soldering wires to the pins and directly soldering to the PCB.What I think you might be after is something like..https://www.usbgear.com/USB-PRODUCT-details.cfm?sku=KWOU004-1&cats=102&catid=102Haven't seen one in Aus yet, but haven't looked too hard.Maybe if you're making up your own cable, use a header pinout the same as on PC motherboards so you could swap to a pre-made one in the future.

author: Richard_Fry
author_rank: Contributor
timestamp: October 08, 2013, 09:42:58 am
content: There's these on Ebay from China, but they're 2 1/1 ft long. For only a few, maybe cut the cable down and reterminate.http://www.ebay.com.au/itm/2-5ft-USB-2-0-B-female-panel-mount-to-5Pin-F-0-1-header-PCB-motherboard-cable-/131013614495?pt=AU_CablesConnectors&hash=item1e81051b9f&_uhb=1

author: HackedFridgeMagnet
author_rank: Super Contributor
timestamp: October 08, 2013, 08:58:03 pm
content: Thanks Richard,That is exactly the format I want. I will give them a try. Hope the quality is good enough.

author: stefanh
author_rank: Contributor
timestamp: October 08, 2013, 10:18:39 pm
content: FrontX have a variety of panel mount internal cables available at different lengths, just a bit more expensive than the ones previously linked on ebay.http://www.frontx.com/store/order_pb.html
Chassis recommendation? - Page 1
Forum section: electronics / projects

author: alank2
author_rank: Super Contributor
timestamp: October 26, 2015, 01:54:55 pm
content: I've been fussing around with a RFTG rubidium module for years, here is a picture:http://www.ebay.com/itm/Lucent-RFTG-m-RB-CDMA-Rubidium-Control-Module-KS-24019L105B-/171022839833?hash=item27d1c17019:m:mzsasPEUOh3lxBFOYsoQaIAMy big problem was trying to decide how to cool it in this giant heat sink box it is in, and I've tried various things and am now giving up on keeping it in this box. It is just too unwieldy, and honestly doesn't cool it very well either. I've found that most of the heat is produced by the LPRO-101 module, and even then, most of that heat is produced in its base plate. By removing the pcb and LPRO-101 and turning them upside down so the base plate is up, I put a small fan on it and it keeps cool to about 35-40 deg C with very little trouble.The bottom line is that I have a GPS board, AVR based control board, and a fan to add to it and I want everything in one box. That would be a vast improvement over the pcb's I have hanging over it with wires going everything.The problem is finding a case big enough at a low price. I've found the 1598J that might be suitable but it might be tight. The RFTG pcb/RB module are about 9" x 6" on their own (1.5" tall). It seems like if you find a suitable instrument chassis, that they are very expensive.My question is - does anyone have ideas about a chassis that is low cost? Something with a detachable front and back is a plus because I can cut the panels on my CNC for the front connectors and management VFD and the back for the fan, power switch, gps antenna, etc.

author: dom0
author_rank: Super Contributor
timestamp: October 26, 2015, 02:26:49 pm
content: Two extruded aluminium heat sinks for the sidepanels, 10 mm aluminium bottom plate to mount the oscillator on. Apply some thermal grease between baseplate and the bottom plate, and between the bottom plate and the heat sinks. 2-3 mm aluminium top/front/rear panels and you're done.
Chattering relay to generate fast transients - How can amplitude be increased? - Page 1
Forum section: electronics / projects

author: AndersJ
author_rank: Frequent Contributor
timestamp: December 08, 2016, 07:28:22 am
content: I have built a chattering relay, trying to simulate Fast Transient Bursts, FTB.It works, but I need a higher output level.I run it at 230 V, and prefer to not go higher.What can I do to increase the output level?

author: Rerouter
author_rank: Super Contributor
timestamp: December 08, 2016, 07:33:45 am
content: add some inductance to ground on the switched side, the increased current spikes will translate to hopefully more impressive voltage spikes,

author: AndersJ
author_rank: Frequent Contributor
timestamp: December 08, 2016, 07:51:39 am
content: An inductance in parallel with the relay coil?And preferable >> Inductance(coil)?Maybe I should scale down to 24 V to simplify finding a suitable additional inductance.Would that set me back as much as adding an inductance, so net result is small?Yes,I know, it depends, of course, but I have no gut feelings in this particular area.Is using a large voltage at all helpful?

author: tautech
author_rank: Super Contributor
timestamp: December 08, 2016, 08:02:50 am
content: They used to be used for LV step up for valve HT supply.You can read about them here:https://en.wikipedia.org/wiki/Vibrator_(electronic)
Cheap 10V source(LTZ 1000A) based on reference designs. - Page 1
Forum section: electronics / projects

author: TristanK
author_rank: Newbie
timestamp: April 29, 2023, 07:37:52 pm
content: Hey,i wonna build my own 10V reference source. My goals for the start is just working and cheap. i want to improve is in future revisions.It would be very help full if someone could overwatch my plans and give me a feed back.thx to all of you

author: Kleinstein
author_rank: Super Contributor
timestamp: April 29, 2023, 07:49:51 pm
content: The LTZ1000A on it's own is not a cheap solution. It makes little sense to skimp on the OP-amps. The suggested LF412 is not working as it is not single supply.A cheap solution for a 1 st test would be more like an LM399.Much of the circuit is hard to read, but looks like the standard circuit - at least it should be.The trim of the resistive divder dowes not look good, with too much effect of the trimmer. The feedmach is also from wrong side of the inductors.The choice of the OP-amp for the output stage is way off.

author: Echo88
author_rank: Frequent Contributor
timestamp: April 30, 2023, 03:13:57 pm
content: Q2 collector is connected to ground and wont work that way. I assume you want to use it as a driver, like done in the Datron schematic?:https://xdevs.com/doc/Datron/4910_4911/4910%20c20090120%20%5B8%5D.pdfSuggest also this design as a reference:https://edms.cern.ch/ui/file/2820336/1/EDA-04061-V4-1_sch.pdfpage 3

author: Dr. Frank
author_rank: Super Contributor
timestamp: April 30, 2023, 04:05:18 pm
content: Here's my opinion:Don't re invent the wheel.Just take any of the many improved circuits in the big thread, chose the cheapest design, components and PCB, plus a suitable case, best is a double shield design, and just assemble the whole stuff. Have a look, how I realised the whole assembly, with either the bare reference, or an additional 10V output as well.The circuit based on Andreas add-ons seems to be the most suitable.A low noise stabiliser and supply is also required.You did not say, what's your basic intent, I.e. tinkering only, or just creating a stable reference, so that would determine your proceedings.Frank
Cheap 120kbps isolation - Page 1
Forum section: electronics / projects

author: ali_asadzadeh
author_rank: Super Contributor
timestamp: November 29, 2019, 12:23:27 pm
content: Hi,I want to isolate a UART, the speed is 115200 baud, the problem for now is the cost of isolation, the cheapest that I could find is CA-IS3721HS, you can find it in lcsc at this linkhttps://lcsc.com/product-detail/Digital-Isolators_Chipanalog-CA-IS3721HS_C428884.htmlThis part is around 0.4136$ @ 100uints.These days that we can find a 0.03$ MCU, why we can not get cheap isolation for low speed,I was thinking of using simple optocouplers like PC817, But I can get around 9600bps with these simple ones, So the question is can we do it with sub 0.1USD total parts, do we have this option? for now only one channel is ok for me too, I mean I can live with only TX from uart too.

author: jhpadjustable
author_rank: Frequent Contributor
timestamp: November 29, 2019, 01:16:14 pm
content: Because isolation requires space and space costs money.How about the PS2701 optoisolator?

author: NiHaoMike
author_rank: Super Contributor
timestamp: November 29, 2019, 01:41:09 pm
content: If you take an optoisolator that exposes the base pin and add a pull down resistor, you'll get better bandwidth.

author: pigrew
author_rank: Frequent Contributor
timestamp: November 29, 2019, 03:50:33 pm
content: Quote from: ali_asadzadeh on November 29, 2019, 12:23:27 pmMy guess is that these devices are not silicon and also that they require more complicated packaging (two separate dice with an optical channel between them). There likely hasn't been a big push for cost optimization.For the "normal" optos (4N series), you need to pay attention to the rise and fall times on the datasheets. You'll want the rise and fall to be at worst 20% of your bit period (so tr+tf < 1.7 us). The PS2701 is still too slow.I was able to find the 6N137 which has an integrated digital receiver for about half the cost of CA-IS3721HS. Its datasheet headline states 10 MBd, so should work fine at 115200. Find clones on LCSC for about US$0.17.

author: ali_asadzadeh
author_rank: Super Contributor
timestamp: November 29, 2019, 09:09:20 pm
content: Certainly 6N137 would do the job, But i need something about 3 times cheaper,

author: ali_asadzadeh
author_rank: Super Contributor
timestamp: November 29, 2019, 09:15:46 pm
content: QuoteDo you suggest some part numbers?

author: poorchava
author_rank: Super Contributor
timestamp: December 06, 2019, 03:13:05 pm
content: You can Manchester-encode the uart and couple it using a transformer. You can get a multi-kV isolation that way for relatively cheap (using a tiny toroid or an EE core + TI wire)

author: R_G_B_
author_rank: Frequent Contributor
timestamp: December 07, 2019, 09:52:43 pm
content: It's difficult to achieve the claimed speeds of some of these opto-isolators. Youas well have to think about how you deal with the attenuation and effects on the duty cycle and phase shift.
Cheap 6 dollar eBay timer for UV box - Page 1
Forum section: electronics / projects

author: Arp
author_rank: Unknown
timestamp: February 26, 2014, 09:17:09 pm
content: Got the timer yesterday. Thought I'd give it a go. Did some additional wiring. Moved the 7 segment and added extra buttons.Results are so far:http://youtu.be/7GiJw5kIWG0Seems to work pretty good, and only $6Here is the eBay link if anyone is interested:http://www.ebay.com/itm/12V-Home-Automation-Delay-Timer-Control-Switch-Module-Digital-display-LED-/131013533529?pt=LH_DefaultDomain_0&hash=item1e8103df59

author: Erwin Ried
author_rank: Regular Contributor
timestamp: February 26, 2014, 10:21:52 pm
content: WOW! years ago a timer was ultra expensive, now it is impossible to make anything cheaper with DIY components!

author: johnh
author_rank: Regular Contributor
timestamp: February 27, 2014, 01:08:47 am
content: Do they ship Australia or not?

author: Legit-Design
author_rank: Frequent Contributor
timestamp: February 27, 2014, 01:17:38 am
content: Quote from: johnh on February 27, 2014, 01:08:47 am"Ask a question"Most hong kong/chinese sellers will usually ship to anywhere you want. Even if they didn't bother listing it on the item or there are mistakes in the listing. Same goes for sellers anywhere in the world. It never hurts to ask.Quote from: Arp on February 26, 2014, 09:17:09 pmWhat kind of UV leds are you using and what kind of results are you getting? Do you recommend the same setup for other people?

author: Arp
author_rank: Unknown
timestamp: February 27, 2014, 01:59:15 pm
content: Quote from: Legit-Design on February 27, 2014, 01:17:38 am5mm flat tops found on eBay (http://www.ebay.com/itm/500pcs-x-UV-5mm-Flat-top-LED-Wide-Angle-UV-Purple-Led-Light-lamp-led-2pin-/111106492688?ssPageName=ADME:L:OC:US:3160)Have pretty good results now when the timing is right. Never used tubes, so don't know how they compare, but reckon leds will have the light better distributed.

author: Arp
author_rank: Unknown
timestamp: February 27, 2014, 02:03:21 pm
content: Quote from: Erwin Ried on February 26, 2014, 10:21:52 pmIt's pretty sad. Reminds me of saving money on the bank and having inflation slowly devour it. Better to spend it as soon as you can before it's worthless
cheap 8 layer PCB service - Page 1
Forum section: electronics / projects

author: ali_asadzadeh
author_rank: Super Contributor
timestamp: February 21, 2022, 12:20:55 pm
content: Hi,I want to know if you would recommend a PCB shop in china where the Quality is comparable to JLCPB but can do 8 layers too,I have a normal 5mil/5mil 8 layer design (300m x 150mm), I wonder if it can be done around 200$~250$ range for 5 units.

author: m98
author_rank: Frequent Contributor
timestamp: February 21, 2022, 01:15:50 pm
content: If you about double your budget, PCBWay would be an option. Other than that, multi-cb. European manufacturing, excellent quality, Chinese prices.

author: rpiloverbd
author_rank: Regular Contributor
timestamp: February 21, 2022, 01:39:28 pm
content: Hi, You can consider PCBway or Rayming PCB. They do 8-layered PCBs.

author: ali_asadzadeh
author_rank: Super Contributor
timestamp: February 21, 2022, 03:51:11 pm
content: Thanks for the Suggestions, I know a lot of places would do 8 layers and I have tested quite a few of them, But I want something good and cheap! like jlcpcb

author: Swake
author_rank: Frequent Contributor
timestamp: February 24, 2022, 09:43:48 pm
content: it doesn't come any cheaper than this. If you want it cheaper you'll have to reduce the number of layers or do crazy things like laminating two 4 layer boards together yourself.
Cheap ADC 1GSPS / 4x250MSPS  - Is available from any manufacturer ?   - Page 1
Forum section: electronics / projects

author: Miyuki
author_rank: Frequent Contributor
timestamp: February 29, 2016, 01:52:10 pm
content: Hi,does any manufacturer have in production cheap ADC with 1GSPS / 4x250MSPSand price up to 30$ ?As alternative I have cheap video digitising ADCs which are available at 3$ piece, just that evil routing over multiple packages

author: daqq
author_rank: Super Contributor
timestamp: February 29, 2016, 02:08:14 pm
content: The AD9286BCPZ-500 (http://sk.farnell.com/analog-devices/ad9286bcpz-500/adc-8bit-spi-srl-500m-48lfcsp/dp/1897113) is almost what you need, dual @500MSps. Also, try looking at the pricing directly at the manufacturers site - LT provides this info @ 1k pcs.

author: Lukas
author_rank: Frequent Contributor
timestamp: February 29, 2016, 02:19:44 pm
content: Quote from: Miyuki on February 29, 2016, 01:52:10 pmThe by far cheapest ADC is this range is the HMCAD1511. It's used in the Rigol DS1054Z and many other entry-level DSOs nowadays. It's $65 in one-off quantities.

author: Miyuki
author_rank: Frequent Contributor
timestamp: February 29, 2016, 02:44:52 pm
content: Quote from: Lukas on February 29, 2016, 02:19:44 pmHMCAD1511 I know and is nice chip, but at this price I can have pile of TVP7002PZP (TRIPLE 8-/10-BIT 165-/110-MSPS)And then its a big question what use, I have enough available pins on FPGA to use six of them

author: Scrts
author_rank: Frequent Contributor
timestamp: February 29, 2016, 03:26:08 pm
content: Quote from: Miyuki on February 29, 2016, 02:44:52 pmAre you sure this ADC can output just data samples? Because it seems like it's video ADC and will post-process the data to match television standards. Or your plan is to output RGB color space? Analog video signals also have sync signals in it, so are you sure that this ADC will work without those syncs?

author: Miyuki
author_rank: Frequent Contributor
timestamp: February 29, 2016, 03:29:12 pm
content: It is very flexible, can be run from external clock with with raw data output

author: daqq
author_rank: Super Contributor
timestamp: February 29, 2016, 03:31:48 pm
content: QuoteIf pin count is the only problem see ADCs with a JESD204B serial interface.
Cheap and compact usb hub for Pi Zero - Page 1
Forum section: electronics / projects

author: frenky
author_rank: Unknown
timestamp: November 24, 2016, 08:54:10 am
content: I needed a compact solution for VirtualHere USB Client for my thermal camera.Pi Zero is great but it only has one usb port and I needed two (one for wi-fi dongle and one for thermal camera).I know there are already nice usb hubs for pi zero but most of them are quite pricey and I did not want to wait 2 weeks to get it.So I searched for tiny usb hubs in my local shops and found this one for only 6€:Akasa AK-HB-07BK:Took it apart:I desoldered two ports because I only needed two and made it smaller:Stick it on pi zero with 3M doublesided transparent tape. It's perfect match:And connected power and data lines:I'm really happy with the compact solution.And now I can use my i3 ThermalExpart as a wifi thermal camera (withvirtualhere.comsoftware).
Cheap and Nasty EPROM Programmer - Page 1
Forum section: electronics / projects

author: Raven Luni
author_rank: Contributor
timestamp: June 22, 2018, 08:44:33 pm
content: Greetings,I thought I'd start by posting what I'm working on right now. This is a programmer for AMD Am27C010 EPROMs designed to work with the Raspberry Pi. I got a buch of these ROMs for a ZX81 clone I'm working on (I'll post that at some point) and rather than waste money on a programmer I decided to make one. It's a bit 'how ya doin' as Dave would say but hopefully it will get the job done. The programming voltages it puts out are roughly VCC=6.4V and VPP=12.9V which are within tolerance (datasheet says 6.25 and 12.75 with 0.25 margin either way). The VPP Enable input sets them both to 5V when high.

author: stj
author_rank: Super Contributor
timestamp: June 23, 2018, 12:18:47 pm
content: why 128k for an 8k rom??

author: Raven Luni
author_rank: Contributor
timestamp: June 23, 2018, 10:26:58 pm
content: If I'm ordering a part like that I usually overspec and get a few of it that can be used in different projects. If this goes well I want to try doing a Spectrum.

author: Raven Luni
author_rank: Contributor
timestamp: June 30, 2018, 12:47:26 am
content: Here goes - completely untested. Wish me luck (or start taking bets on whether its going to blow up my raspberry pi) :p

author: james_s
author_rank: Super Contributor
timestamp: June 30, 2018, 05:42:47 pm
content: Seems like it would be easier to use something like the TL866. If you're feeling really ambitious it would be great if someone could write a new program to operate it. The one it comes with works but it's Windows only and full of Engrish.

author: Raven Luni
author_rank: Contributor
timestamp: July 01, 2018, 01:22:52 am
content: Interesting. I might look into that at some point.
Cheap Audio codec suggestion - Page 1
Forum section: electronics / projects

author: ali_asadzadeh
author_rank: Super Contributor
timestamp: August 19, 2019, 06:59:06 pm
content: Hi,I want to build an audio mixer for a hobby project, It would have at least 8-16 audio input channels, and about the same audio outputs, I think the CS4344 is very cheap and good candidate for the DAC part, but for the ADC part's I want something in sub 1$ price, I prefer I2S and If it can handle line in and a MIC it would be very nice.Do we have Chinese Codec manufacturers? what are the cheap options out there? a single channel codec is perfect,Note: I plan to do all the DSP with a GOWIN FPGA or use a cheap CortexM4 on each channel.Any Ideas are welcome
Cheap camera with LVDS CameraLink interface - Page 1
Forum section: electronics / projects

author: clovek
author_rank: Newbie
timestamp: September 27, 2018, 01:10:14 pm
content: I am searching for any cheap camera that can produce LVDS CameraLink interface data.In ideal case somethin with similar interfaces as XBC-KZ10 from InterTest or FCB-EV7100 from SONY i.e. commandable by serial protocol VISCA.Do anyone know source of camera with this intefaces? Or at least some camera capable to source FULL-HD image on LVDS?I was searching on cell phone parts, laptop parts but it has always different interfaces. Or do you know if some car dashboard camera or similar chteap device has internal LVDS?
Cheap charcoal fume extractor made out of computer PSU  - Page 1
Forum section: electronics / projects

author: DaMaDo
author_rank: Contributor
timestamp: December 31, 2011, 10:57:20 pm
content: I was taking apart a 3 yr old 1000 watt computer PSU to desolder some parts, etc and realized it would make a great fume extractor. I also had more charcoal sheet than I'll ever need since the order for my air purifier came with an astounding amount (For just $1.50).So here's what I made:After removing all the electronics. It's a 140mm fan.Cut a peice of charcoal sheet to fit in the exhaust and used a plate that was originally on the fan to hold the sheet in placeStays put wellUsed some carbon fiber looking sticker thing to seal the bottomExhaust side when put back togetherWorking on my desk. Good suction at 12v.I reattached the switch that turns on the LEDs..can be white or blue or off.I might eventually attach a nice plug into the box with it's own power switch so that the wires aren't hanging out.

author: eternal_noob
author_rank: Regular Contributor
timestamp: January 01, 2012, 12:21:43 pm
content: That's excellent reuse of old parts. I love it.I have a habit of using stuff from old video player, TV's, radios and whatnot, myself. It's kinda fun making old shit into something useful.