Annoying Power supply

I have one of those cheap rebadged power supply and if you want to buy one be notified that the current pot is a fucking single turn pot, so you can’t tune reasonably well the output current and sometimes it will send out hundred of mA without any kind of issues if you had the infortunate idea of tweaking the pot. Besides the ampmeter is scaled at 10 of mA and for low current application it’s useless !!

However the volt pot is a multi-tour pot. Don’t ask me why, I don’t know. It’s cheap for sure but it remains that It’s a real pain in the ass to work with !  I may take it appart and replace the current pot.

Also note the second channel layout is a mirror of the first one. So the pot layout makes any kind of sens for an efficient use.

On the other hand, I also have this old well-built power supply that works wonderfully well with a nice feeling and it’s a real pleasure to work with it. However, I can’t because most of the time I need a dual power supply ! The only complain is the odd construction technique.

So, choose your tool with care but having low budget isn’t helping !

Source (and if you want to buy one) :



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3 responses to “Annoying Power supply

  1. Gordon

    If your old power supply can output 30 volts, it’s quite easy to convert to +/- 15 V for opamps using a tda2030a as a high power supply rail splitter. Basically the tda2030a is an opamp with high current output. Configure it as a unity gain buffer and connect the +ve input to a potential divider, for exactly half of Vs ( 15 volts, in this case ). Because it is a follower you can easily get +/- 9, +/-10, +/-12 Volts, etc, as needed. The tda2030 needs to be on a heatsink if there’s going to be significant current in the 0 volt rail.

  2. Gordon

    My bench PS allows you to set the current digitally, the downside is that it can only be set to certain preset values, starting at 20 mA ( not ideal ) going up in a log type manner, 2, 5, 10.
    It is hard to adjust it by mistake though, which is a good thing. Some of the guys on, reckon that you are better to by a used PS, made by one of the serious manufacturers, like, HP / Agilent, Keithly, etc.

  3. Nice little trick with the TDA !
    actually seeing the ebay offer I’m considering buying it and selling the Temma. Connected in series I could get my dual power supply for half the space.

    Besides, I never need more than 1A even for heavy digital circuit.

    Indeed old gear are more interesting to some aspects. Cheap, easy to repair and design with someking of care for the end user. But if you need something more sophisticated you’re kind of screwed unless you have the money for big name product.

    But the TEMMA is very unpleasant for me. I think I’ll end up building my own tool as well or modifying existing one.

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