Topward tps4000 update - Page 1
Forum section: electronics / testgear

author: vlelectroniclab
author_rank: Contributor
timestamp: February 02, 2025, 07:38:32 pm
content: Hello everyone,I have many analog topward tps4000 power supplies.They are excellent power supplies, they always work and never break.The analog indicators are not precise and often need adjustment, however the volt potentiometer is very sensitive and sometimes I have difficulty adjusting it correctly.I would like to update them with digital displays and put multi-turn potentiometers, what do you think?I attach the manual with the diagrams.I was thinking of instrumentation amplifiers to read voltage and current which then in turn go to the 4ch of the ads1115 which then communicates with a raspberry pi pico w.Then I wanted to put a display for each indicator, I still have to figure out how to do it.What do you think? any advice is welcome.Regards Vito

author: ledtester
author_rank: Super Contributor
timestamp: February 02, 2025, 10:47:05 pm
content: You may find 10-turn pots a bit tedious to use in practice since changing the voltage up and down on a power supply is something you do quite frequently.I would look at a coarse/fine arrangement. I believe you can get dual independent pots on a single shaft which have concentric controls for each pot - ie the two pots are _not_ ganged.Maybe this is what I'm thinking of:https://www.amazon.com/Alnicov-Guitar-Stacked-Concentric-Potentiometer/dp/B08MPZSFJK/Update:For measuring current (and also possibly voltage) I would look at the digital power monitors from TI:https://www.ti.com/amplifier-circuit/current-sense/digital-power-monitors/overview.htmlThey are high-side power monitors with an I2C interface and can operate as high as 48V for some chips.

author: lowimpedance
author_rank: Super Contributor
timestamp: February 03, 2025, 12:04:33 am
content: And if concentric shaft pots of the right values are not available , there are 3 turn pots which would be quicker than 10 turn types. Sample link from Mouser below. Pricey, but if your going to the effort of digitizing the displays etc then ..... why not ! The expense will be long forgotten when you get long service from the supplies.I also have a few of these supplies and agree they are good value solid performers, with a little bit of maintenance ,(ie the electrolytic caps dry out), they keep on chugging away.I am happy to just use a DMM to set the voltage.https://au.mouser.com/c/passive-components/potentiometers-trimmers-rheostats/precision-potentiometers/?number%20of%20turns=3%20Turn

author: Andy Watson
author_rank: Super Contributor
timestamp: February 03, 2025, 12:09:07 am
content: Depnds on how you want ot use this supply. If you want to use it as a general purpose bench supply, then I agree with Ledtester, ten turn pots become very tedious, very quickly.QuoteNo, this is not a good option. Remember that you have two independant supplies, they do not share a common reference/ground. Even in tracking mode, they do not have the same reference/ground potential. I think a pi is overekill for this problem (unless you have greater plans for communication?) I would look towards obtaining DVM modules to replace each meter (remember that they will also need a power source).

author: garrettm
author_rank: Frequent Contributor
timestamp: February 03, 2025, 01:02:16 am
content: Personally, I don't think 10-turn pots are all that annoying. I have swapped quite a few 1-turn pots with 10-turns because I enjoy having the increased resolution. But if you do vary the voltage frequently, then I can see it being annoying--especially if you have an impatient personality. In general, I don't change the output voltage all that much. Mainly use 5, +-12, +-15, +-18 volts for powering prototypes and sometimes to charge batteries. But I do have quite a few PSUs that I dedicate to specific applications, so the need for a one-size-fits-all PSU isn't something I worry about.Analog supplies are electrically "quiet" by virtue of their simplicity, "upgrading" them with digital displays--if not carefully designed--can make them no better than buying a newer PSU with built-in digital controls and display. So while the increased readback resolution is nice, the clock of a uC (for example) can radiate and get picked up on the output as well as other switching noise from the display.I just depends on what you do with the PSU. If you are using it to test OP-AMPs and use sensitive equipment like a 24bit ADC to do FFTs then you will see added noise. If you just charge batteries and power random equipment that you don't have a power brick for, then it's probably fine. Really depends on the application and your expectations regarding performance. Sometimes it's better to just buy an new PSU and sell your old ones. Maybe keep one fully analog unit for special low noise applications and get a nice general purpose PSU for quick testing at the work bench. That's what I've done. Trying to "upgrade" an older design often ends up with a worse device in the end.

author: vlelectroniclab
author_rank: Contributor
timestamp: February 03, 2025, 07:43:56 am
content: HI, thanks everyone for the advice. for the potentiometers I was thinking of the 3-turn ones, as you say with 10 it will be boring. put 4 dvm no, because in the future I want to view on smartphone. as Andy Watson says I don't agree with any mass... How do I use just one ADC? I use the power supply to power sections of systems in mobile machines (excavator, loader, bobcat, etc.) so sometimes it happens to disconnect the 5v power supply from the ecu and power it with the power supply. I wanted to use a pi pico w because later I wanted to make an app for smartphones, so that even if I'm far away from the power supply looking for the fault I can keep it under control via smartphone (I'm only interested in reading and if possible accessing and switching off the selected channel). thanks and regards Vito

author: ledtester
author_rank: Super Contributor
timestamp: February 03, 2025, 11:29:13 am
content: Quote from: vlelectroniclab on February 03, 2025, 07:43:56 amHere's an idea for just reading voltage and current...The TC66C is a "USB tester" -- it measures the voltage and current flowing through a USB power connection.But, it can also be used as a 5.5 digit multimeter:Using the TC66 USB tester as a $30 5½ digit precision multi-meter -- TheHWcavehttps://youtu.be/iZ5JjA6DoZgand its data can be read from a Windows or Linux via a USB connection or Bluetooth:https://www.sigrok.org/wiki/RDTech_TC66Chttps://github.com/TheHWcave/TC66https://budgetlightforum.com/t/tc66c-a-powerful-type-c-usb-tester/56165So you could insert this between the power supply and your application, have a small Raspberry Pi-like computer read data from it and forward it to you via Wifi.Here's a video that goes into more detail about the TC66C:Ruideng TC66 / TC66C USB Type-C Tester - Way too good for just USB! -- TheHWcavehttps://youtu.be/rOlhibDUJgsA similar idea is to use this:DC 0-420V Tuya WiFi Smart Lithium Battery Capacity Detection Tester DC digital Display Current Voltage Coulomb Power Meter DT20Whttps://www.aliexpress.us/item/3256806982619978.htmlIt was design to monitor a battery pack, but it but it can be used as just a DC power meter. It has Wifi and comes with a phone app but doesn't appear to be as open as the TC66C.