Author Topic: CODA Relay Bypass Help  (Read 213 times)

Bio77

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CODA Relay Bypass Help
« on: June 20, 2022, 06:04:06 PM »
I've been trying to implement a CODA relay bypass  for awhile.

https://www.coda-effects.com/2016/04/relay-bypass-conception-and-relay.html

I think I have the microcontroller programmed correctly.  I can set everything up on a breadboard and get it to work. The only difference is that on the BB I use the 5V regulated bus.   However, when I populate the PCB the relay won't switch.  The LED is working and I measure 3V or 0V across the diode, depending on which state the MC is in.  I'm stumped. 

Can anyone spot anything wrong with my schematic or layout?  I know the silkscreen for regulator is backwards, I installed it correctly on the PCB. 



gordo

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Re: CODA Relay Bypass Help
« Reply #1 on: June 20, 2022, 06:41:45 PM »
I think you made the same mistake I did.  The chipís pin 8 needs to go to ground.
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jimilee

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Re: CODA Relay Bypass Help
« Reply #2 on: June 20, 2022, 08:01:09 PM »
I think you made the same mistake I did.  The chipís pin 8 needs to go to ground.
Looks like it is.


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Derpinador

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Re: CODA Relay Bypass Help
« Reply #3 on: June 20, 2022, 08:16:18 PM »
Think he's trying to see where he's losing 2 volts from when it's on the BB vs wired up as a circuit. Likely needs that 1~2 volts to magnetize the coil in the relay. If you will it's like trying to use a 10w amp to power a 100watt 15in speaker, there's some movement but you'd have to look directly at it to see. I'll stare at it for a few days... I'm a carpenter not a an engineer  ;D

post study edit

looked at it a few minutes, which way is the relay connecting the circuit? IF the relay is a straight back and forth, like positions 3,4 connecting same time as 7,8 maybe 3,4 are swapped? or is it a rocker type connection inside? The 1 on the BB might be the rocker type but is the 1 on the pcb as well?
« Last Edit: June 20, 2022, 08:32:09 PM by Derpinador »

Aentons

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Re: CODA Relay Bypass Help
« Reply #4 on: June 20, 2022, 09:34:19 PM »
I think you have c1 on the 5v side rather than the 9v side of the regulator. Not sure if that matters

Bio77

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Re: CODA Relay Bypass Help
« Reply #5 on: June 21, 2022, 10:17:54 AM »
Thanks everyone, I appreciate the conversations.

I think you have c1 on the 5v side rather than the 9v side of the regulator. Not sure if that matters
I did this intentionally, since I am usually taking 9V from the main PCB and there is always power filtering, reservoir caps, and a protection diode. I can try to remove it.  It also wasn't on the BB.

looked at it a few minutes, which way is the relay connecting the circuit? IF the relay is a straight back and forth, like positions 3,4 connecting same time as 7,8 maybe 3,4 are swapped? or is it a rocker type connection inside? The 1 on the BB might be the rocker type but is the 1 on the pcb as well?
My understanding of the relay from the data sheet is that it is a rocker, basically two SPDTs between 2,3,4 and 7,8,9.  I'm wondering if there is a difference in current between the BB and PCB.  Since the magnetic field in the coil is proportional current.  Maybe adding a transistor in the next version would help.

I noticed Brian's Softy has a transistor at the relay, but it looks to be configured as a switch rather than a current amplifier.  Also, I know others have gotten this to work without one. 

Derpinador

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Re: CODA Relay Bypass Help
« Reply #6 on: June 21, 2022, 01:18:14 PM »
It might help, but I've also seen relays for automotive use, box never opened dead on the store shelf.

That was the 1st thing I noticed you designed for 5v but the 1 spot was reading 3 or zilch. Try just a jumper instead of c1?

Aentons

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Re: CODA Relay Bypass Help
« Reply #7 on: June 21, 2022, 02:16:07 PM »
Are you getting 5V on pin1 of the PIC?
What about the PIC pin 2 to 8?

Bio77

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Re: CODA Relay Bypass Help
« Reply #8 on: June 21, 2022, 07:43:21 PM »
I'm getting 5V on pin 1 in both cases.  Below are the PIC voltages in the on and off states:

Pin  off    on
1     5      5
2     0      3.5
3     0      0.5
4     1.2   1.2
5     0      0.22
6     5      5
7     0      5
8     0      0

pin 5 is part of anti-pop system that I chose not to add.


Aentons

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Re: CODA Relay Bypass Help
« Reply #9 on: June 21, 2022, 08:04:50 PM »
What relay are you actually using? Your board has the footprint of a 10 pin and the NA5W-K pinout is a 10 pin but has the foot print of a 12 pin with pins 2 &11 missing

Bio77

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Re: CODA Relay Bypass Help
« Reply #10 on: June 22, 2022, 10:02:42 AM »
Sorry for the confusion.  The schematic I posted yesterday was to show the anti-pop circuitry I'm not using.  The OP schematic is my actual PCB.  It is using Fujitsu A-4.5W-K. Itís non-latching.

https://www.mouser.com/ProductDetail/Fujitsu/A-45W-K?qs=w1bwiar3BoIWMoV30P37UQ%3D%3D


Aentons

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Re: CODA Relay Bypass Help
« Reply #11 on: June 22, 2022, 10:25:52 AM »
I think you have the relay sides reversed on your board. The datasheet shows a bottom view of the pins

Bio77

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Re: CODA Relay Bypass Help
« Reply #12 on: June 22, 2022, 11:03:41 AM »
You rule! ;D  That makes sense.  I guess when I set it up on the BB I just chose pin 1 of the relay as the + side and didn't notice that it's flipped on the PCB.  I even have the square pin footprint flipped  :P

I can flip the relay to the back side of the board to confirm. 

Thanks you!