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 (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.
(https://imagizer.imageshack.com/img923/2935/QheaXm.png)
(https://imagizer.imageshack.com/img922/319/sqzvLq.png)
I think you made the same mistake I did. The chip's pin 8 needs to go to ground.
Quote from: gordo on June 21, 2022, 12:41:45 AM
I think you made the same mistake I did. The chip's pin 8 needs to go to ground.
Looks like it is.
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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?
I think you have c1 on the 5v side rather than the 9v side of the regulator. Not sure if that matters
Thanks everyone, I appreciate the conversations.
Quote from: Aentons on June 21, 2022, 03:34:19 AM
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.
Quote from: Derpinador on June 21, 2022, 02:16:18 AM
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.
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?
Are you getting 5V on pin1 of the PIC?
What about the PIC pin 2 to 8?
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.
(https://imagizer.imageshack.com/img924/3315/MOBAJn.jpg)
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
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. It's non-latching.
https://www.mouser.com/ProductDetail/Fujitsu/A-45W-K?qs=w1bwiar3BoIWMoV30P37UQ%3D%3D (https://www.mouser.com/ProductDetail/Fujitsu/A-45W-K?qs=w1bwiar3BoIWMoV30P37UQ%3D%3D)
(https://imagizer.imageshack.com/img924/4075/icNmh3.jpg)
I think you have the relay sides reversed on your board. The datasheet shows a bottom view of the pins
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!