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Homebrew Equipment A place to show, design and discuss the weird and wonderful electronic creations from the hands of individual members. |
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27th Mar 2019, 1:32 am | #21 |
No Longer a Member
Join Date: Oct 2016
Location: Maroochydore, Queensland, Australia.
Posts: 2,679
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Re: Low frequency indicator?
...but the original request was for the circuit to produce a DC voltage. The 555 circuit only works because the integration is carried out by the meter movement. The circuit config I suggested produces the DC voltage, proportional to frequency that was requested, and it can all easily be done with "one IC" a quad op amp.
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27th Mar 2019, 2:48 am | #22 |
No Longer a Member
Join Date: Oct 2016
Location: Maroochydore, Queensland, Australia.
Posts: 2,679
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Re: Low frequency indicator?
Actually, now I think about it, the perfect IC for this job is the National Semiconductor LM3900. A vintage quad OP amp which is a Norton current differencing op amp.
I'm pretty sure that in the original NS Application notes, for the LM3900, they included a great circuit for a frequency to voltage converter. I can't attach it as I'm on a limited mobile device (limited by the operator no doubt), but if you look it up on Google, these op amps are very convenient for applications in the frequency spectrum you require and very easy to use and would make a terrific solution. |
27th Mar 2019, 7:25 am | #23 |
Nonode
Join Date: Oct 2010
Location: Tintinara, South Australia, Australia
Posts: 2,342
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Re: Low frequency indicator?
My mistake, I had it in my mind a meter was being used for some reason, sorry.
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