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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets. |
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24th Feb 2021, 12:26 pm | #1 |
Octode
Join Date: Mar 2015
Location: Yorkshire, England.
Posts: 1,301
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Audio output meter.
I'm about to start making Paul's Audio output meter and have just received the meter movement from China. They sent a 0-500 uA by mistake!
Here is the required r/c for R1 and C2. 0-100 uA 47K and 1uf. 0-250 uA 18K and 2uf. Based on these figures, how about 0-500 uA 9K and 5uf ? I'd like to use as much of the scale as possible to make it easier to see small movements. Any other thoughts?
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Regards, Ken. BVWS member |
24th Feb 2021, 10:12 pm | #2 |
Hexode
Join Date: Oct 2019
Location: Weymouth, Dorset, UK.
Posts: 475
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Re: Audio output meter.
R1 is 18k.
Replace it with an 8.2k and place a 10k preset in series with the meter movement. Adjust the preset to the desired level. That will give you a decent scale to work with. The voltage doubler won't be affected, I wouldn't think. |
25th Feb 2021, 2:34 pm | #3 |
Octode
Join Date: Mar 2015
Location: Yorkshire, England.
Posts: 1,301
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Re: Audio output meter.
Thanks Jon, that's an elegant solution!
I'm about to attempt my first alignment on one of a pair of Bush VTR 103's, starting with the tatty one which I'm using as a test bed before moving on to a very good condition (complete with red-topped aerial) example. I'll post my results in the next few weeks...
__________________
Regards, Ken. BVWS member |
25th Feb 2021, 6:38 pm | #4 |
Guest
Posts: n/a
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Re: Audio output meter.
A lot of overthinking going on, all you need is an indicator of a peak, the absolute range doesn't matter. If you can see the peak it is good enough.
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25th Feb 2021, 7:21 pm | #5 |
Octode
Join Date: Mar 2015
Location: Yorkshire, England.
Posts: 1,301
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Re: Audio output meter.
Me, overthinking? That's a first!
But yes, I agree.
__________________
Regards, Ken. BVWS member |