EEVblog Electronics Community Forum
Electronics => Projects, Designs, and Technical Stuff => Topic started by: Wallace Gasiewicz on August 24, 2024, 09:47:34 pm
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I rebuilt an old Lambda Lab PS and my ruthless appropriation of other peoples schematics has paid off. The thing works pretty well and volt and amp adjusts work. It does drift and at least one cause of this is my volt standard, a 7.2 V Zener. If I even blow on it the volts change. I would like to replace this part with something a bit more stable. Drift really is not a terrible problem since it is in milli volts but it bothers me.
I think that I can easily put in a LM399. I think that would work. There are some on ebay from China. Any advice on using one of these?
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Total overkill. It's a PSU, not a lab reference.
Use a TL431 with a couple of resistors to set the voltage.
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I rather like my Power Designs 2020, both aesthetically and because it is based around an LM399 .
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For your purposes, TL431?
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https://www.eevblog.com/forum/metrology/is-tl431-good-for-reference-in-19-999-counts-voltmeter-any-variants/ (https://www.eevblog.com/forum/metrology/is-tl431-good-for-reference-in-19-999-counts-voltmeter-any-variants/)
Oh, I didn’t even read the second line of Benta’s post apparently.
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Although I like the sound of "total overkill", I think I have a TL431 around here somewhere..
Think I will give it a go soon. This is just a Lab PS and is used every week or so. I used Multi turn Bourns pots for the adjustments because I have some and I use the PS to provide some finicky voltages sometimes.
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I rather like my Power Designs 2020, both aesthetically and because it is based around an LM399 .
Yes, they sure are pretty. I was tempted to buy one, but gathered that they were hard-wired for 110V operation. Is it not so?
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I rather like my Power Designs 2020, both aesthetically and because it is based around an LM399 .
Yes, they sure are pretty. I was tempted to buy one, but gathered that they were hard-wired for 110V operation. Is it not so?
Many Power Designs PSUs have 110V only transformers.
The 2020 transformer has two primary windings. Hence you can use the usual technique of resoldering the primary wires so the primaries are in series (rather than parallel) turns them into 220V inputs.
For any PD device, I would check the schematic carefully before purchase.