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Author Topic: DuinoVOX schematic question  (Read 725 times)
KJ6DRG
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Posts: 81




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« on: December 01, 2017, 12:48:13 PM »

Kevin KB9RLW details the DuinoVOX (Arduino-based USB interface) on YouTube and the schematic can be found here: https://2.bp.blogspot.com/-YbPcj8k8cM0/V7t14nLsvJI/AAAAAAAAB1k/htV-BIx5jmQFRJyyOcTbgpkVUC6cF86NACLcB/s1600/Schematic.png

My question is regarding the capacitors. In his video Kevin mentions that he used non-polarized caps for C1 and C2 but that builders would be fine using regular electrolytics. Ok, that I understand. C3 shows polarization on the schematic so I assume I could use a regular electrolytic cap there. But looking at the diagram I can't tell what type of capacitors would work best for C4 and C5. Anybody ever build one of these and wanna clue me in here?

I'm pretty new to "real" electronics (only built kits before) so my understanding is probably less than basic.

Thanks everyone,
Michael N6MST
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AA4PB
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Posts: 14354




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« Reply #1 on: December 01, 2017, 01:47:11 PM »

C4 - most any 0.22 ufd cap at 15V or more will work okay. That small of a value will NOT be an electrolytic so it will not be polarized. A film capacitor is pretty common.

C5 - I'd recommend a ceramic capacitor because this is primarily an RF bypass to prevent RF from getting into the PTT circuit. I'd suggest 25V or so as it needs to be able to handle your maximum open-circuit PTT voltage from the radio.
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Bob  AA4PB
Garrisonville, VA
KJ6DRG
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Posts: 81




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« Reply #2 on: December 01, 2017, 09:22:49 PM »

C4 - most any 0.22 ufd cap at 15V or more will work okay. That small of a value will NOT be an electrolytic so it will not be polarized. A film capacitor is pretty common.

C5 - I'd recommend a ceramic capacitor because this is primarily an RF bypass to prevent RF from getting into the PTT circuit. I'd suggest 25V or so as it needs to be able to handle your maximum open-circuit PTT voltage from the radio.


Thank you for the info. I've got about $30 ordered from China, time to hurry up and wait for the slow boat. I ordered a few assortments of parts that included all the parts I need for this project, I will have hundreds of parts leftover for future projects!

Michael N6MST
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AA4PB
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Posts: 14354




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« Reply #3 on: December 02, 2017, 04:44:23 AM »

If you miss some part(s) you might want to consider www.mouserelectronics.com, good for low quantities and quick service. Digikey is also good but requires a $25 minimum order or a handling fee.

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Bob  AA4PB
Garrisonville, VA
AE8RS
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Posts: 43




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« Reply #4 on: December 08, 2017, 05:31:28 AM »

I've also been having good luck with Arrow Electronics. Their prices are very competitive and free shipping on everything. If you spend more than $20, it's free overnight shipping right now.
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