DIY fet voltmeter OZ7HX 1975 dual jfet dual npn test teardown

Made by OZ7HX Mogens back in 1975, sadly someone dropped alot of SALT on this unit, but i was able to clean it, and lucky me, the instrument still works, 10Meg input impedance , and it is very accurate, impressive. only 0.9 watt mains usage, see also the cute mains power switch solution.
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#diyelectronics
#teardown
#vintage
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I use auto generated subs, I go thru them my self, but i am far from perfect at finding all errors, so if you find errors worth fixing, please comment (or PM) with the TIME in the video you saw the error, i will be happy to fix it. This also apply to the Danish version.
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(Thanks to all my Sponsors / Traders / Swappers / Sellers / Buyers, without your support and constant flow of cool items in/out, none of this would be possible)

[Edisson.]

Hi Thomas, that's beautifully made, I'm always happy with these amateur products, if they're this beautifully made. I have a small idea, if he took a combined socket, then when modifying, the base of the double socket will overlap the original holes and a double connector can be used.

Nice day 🙂 Tom

[TryonoTeknikJog]

I apreciate your review about DIY project..not only famous brand 😆

[joseppuig]

Yeah, simple stabilizers with a zener like that, drift their output voltage over temperature changes.
This nice instrument would benefit from using an LM723 in that supply part. And it's a part typical of that era.