Here is v4:
GitHub - pepaslabs/abx-tayda: A relay board for performing blind A/B testing of two audio sources.
- Use 2N3906 PNP transistors rather than BS250 P-channel MOSFETs
- Use wider traces for the signal path
GitHub - pepaslabs/abx-tayda: A relay board for performing blind A/B testing of two audio sources.
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Thank you for all the updates 😀. I've had a look at the latest schematic - I see the P-channel Arduino pins each have a 100k resistor in series except PCH4 on D01 / TX1, which connects directly to the base of Q7. Is this correct?
Whoa good catch! Each PNP should have a 10k base resistor, but one of them is missing! I suppose it is lucky that I haven’t ordered updated boards yet 🙂
Thanks!
Thanks!
Glad to help!
I have some ideas for the unused pins - would you prefer I put them here or create a separate thread?
I have some ideas for the unused pins - would you prefer I put them here or create a separate thread?
Awesome, thank you!
With a couple of switches one could do level matching. The ADC has enough resolution for pretty tight matching .
Use one of the remaining analog pins to set a reference level, switch to the other input, read the signal level while adjusting and light an LED when it's the same as the reference level.
With headphone amps you'd do the adjustments on the amplifier. For use with line-level sources an added potentiometer would be needed.
With a couple of switches one could do level matching. The ADC has enough resolution for pretty tight matching .
Use one of the remaining analog pins to set a reference level, switch to the other input, read the signal level while adjusting and light an LED when it's the same as the reference level.
With headphone amps you'd do the adjustments on the amplifier. For use with line-level sources an added potentiometer would be needed.
Very clever!
This is a bit of a spoiler, but I also have plans to make and inline dB meter (you tell it the sensitivity rating of your headphones and it translates the signal level into dab). Would also be handy for volume matching!
This is a bit of a spoiler, but I also have plans to make and inline dB meter (you tell it the sensitivity rating of your headphones and it translates the signal level into dab). Would also be handy for volume matching!
Aha! Very cool!
Another thought - have you considered a driver chip such as the ULN2803 or DRV777 to control the relays? Obviates the need for transistors and diodes. It won't look as cool though.
edit: I forgot your need for Tayda as a source - the ULN2803 is available from there for $0.48
edit edit: hmm a driver IC doesn't solve the relay coil voltage problem
.
Another thought - have you considered a driver chip such as the ULN2803 or DRV777 to control the relays? Obviates the need for transistors and diodes. It won't look as cool though.
edit: I forgot your need for Tayda as a source - the ULN2803 is available from there for $0.48
edit edit: hmm a driver IC doesn't solve the relay coil voltage problem
.
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Oh that's an interesting approach! It would conserve some board space, and if you were using oshpark that would definitely save some money.
However, I have really loved learning from simple DIY circuits, especially those which leverage "jellybean" and discrete parts. Plus, the DIY'er gets to stock up on these "jellybean" parts which they can use in other circuits.
That said, I could certainly see making a variant of this board, which used parts from digikey, and didn't shy away from integrated solutions 🙂 Or maybe even 😱 an SMD version
😀
However, I have really loved learning from simple DIY circuits, especially those which leverage "jellybean" and discrete parts. Plus, the DIY'er gets to stock up on these "jellybean" parts which they can use in other circuits.
That said, I could certainly see making a variant of this board, which used parts from digikey, and didn't shy away from integrated solutions 🙂 Or maybe even 😱 an SMD version
😀
I totally get ya - there is a satisfaction one gets when doing something from first principles 😀
SMD though... heresy!
SMD though... heresy!
Here's v4.1, with the missing PNP base resistor. 🙂
GitHub - pepaslabs/abx-tayda: A relay board for performing blind A/B testing of two audio sources.
This update was a bit delayed as I was working on another board to bundle into a JLC PCB order.
GitHub - pepaslabs/abx-tayda: A relay board for performing blind A/B testing of two audio sources.
This update was a bit delayed as I was working on another board to bundle into a JLC PCB order.
