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TOPIC: building a hearing aid extra PCboards

Re: building a hearing aid extra PCboards 7 years 1 week ago #16162

  • MrDEB
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Am having PCboards made for a hearing device (beats the $5,000+ of conventional aids)but I only need one maybe two boards. Itead cost is $29 w/ shipping aprox while Dorkboards is $32.50. Boards are 84mm x 50mm.
If anyone wants a board (going w/ Dorkboards for faster service) I will have an extra board.
Have attached the schematic for reference.
Parts should cost $65 plus an enclosure.
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Re: building a hearing aid extra PCboards 7 years 1 week ago #11081

  • RangerBob
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Had a quick peek and I have a couple of points I noticed:

Could just be your Schematic capture package not showing it, but what does the LM2931 actually do? Its output net is named V+ but everything that's got a V+ input is connected to the V+-sw net (the LM2931 input net), or am I missing something?. If this is intentional, then what's your battery voltage as those OPA4364's are only good to 5.5v and the LM2931 dropout voltage can be up to 0.6V (assuming you are using a 5v part as indicated).

Also Port3 doesn't seem to connect to anything but ground, or is this intentional?

Hope this helps!

Re: building a hearing aid extra PCboards 7 years 1 week ago #11083

  • MrDEB
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The schematic capature is not to good. Tried several different things but?/
The LM2931 is a LDO voltage regulator. The battery voltage is 9v.
Have BATTERY to V+ then to V+-sw (the V+-sw is anything after the power switch. I know it is kinda confusing even while I was trying o figure out what I was trying to do.
here is a better updated image http://www.electro-tech-online.com/atta ... g-rev8.jpg
I got LOTS of advice from AudioGuru. Very well versed in audio electronics.

Re: building a hearing aid extra PCboards 7 years 1 week ago #11085

  • RangerBob
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Following that link ... Yup, a vast improvement.

Have BATTERY to V+ then to V+-sw (the V+-sw is anything after the power switch. I know it is kinda confusing even while I was trying o figure out what I was trying to do.

Yes, I can see what you are trying to achieve but your legible schematic does not show that. All the IC's are being powered by V+-sw at 9 volts, according to the schematic. Battery (netname: battery) -> Switched (V+-sw) -> IC's + regulator! The regulator powers nothing and the Opamps go Poof!

Re: building a hearing aid extra PCboards 7 years 1 week ago #11059

  • MrDEB
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THANKS I missed the connection you mentioned. I ordered boards this morning but if I can't get them revised I can hard wire to achieve desired results. Looking at the pcboard design I see I have nothing connected to the regulator output.
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