SOLVED Basic Relay Latching Bypass with 18v power source

[thesoundofjusticefx]

Good morning brain trust. I built a Parthenon (Wampler pantheon blues breaker) with all components able to run at 18v. I added a relay latching bypass to it. I'm not sure why I'm getting occasional volume drops (not completely cut out, nor is the pedal losing power) and some volume surges (level from low to high) when the pedal has an 18v power source. Looking at the schematics of the relay and reading the datasheets of the 78l09/NE555/Kemet EA2-5SNJ Relay I shouldn't have any problems with 18v. I have built several pedals with the the relay latching board with zero problems and all the same components on each one but they all had 9v power source. I built it for a friend so I don't have it with me. Even though I haven't tested the current consumption yet, I'm expecting to give it 100ma. What am I missing? Thanks!

 

[Stickman393]

Hmmm.

Yeah, not really seeing a reason why the relay bypass would not be fully compatible with an 18v power supply. The 78L09 that provides the +9vdc rail for the unit will work just fine with an 18vdc input.

Functionally, as far as the signal path is concerned, there is no real difference between how the relay and the switch handle routing the input and output connections.

The only times a latching relay will pull significantly more current than stock is in the few milliseconds during which the magnetic coil of the relay is active. That is: when the contacts are switching positions.

I suspect that something else is happening here: a flaky connection...maybe. I'd poke around and re-flow the connections that you made during the mod.

 

[JamieJ]

Looking at the data sheet this relay looks compatible with this build even though a TQ2-L-5V is recommended (and impossible to get hold of).

Did you test the pedal without the relay board attached to narrow it down to see if it definitely is the relay board or main PCB?

Can you post some clear pictures of the board when you get the pedal back.

 

[Stickman393]

^true that is what the documents call for, but functionally speaking the Panasonic relay is identical to the KEMET relay. 5v coil, same form factor and contact arrangement, latching single coil type.

The relay consumes 100mw when active, meaning we're talking about a transient spike of 11.11ma at the coil itself. Not a whole lot, and we're talking about a little over half that on the 18v side...but again, since it's latching that current spike is only a blip.

You said that this only happens when you use the 18vdc power supply, right? Is that power supply chained to anything else?

 

[thesoundofjusticefx]

^true that is what the documents call for, but functionally speaking the Panasonic relay is identical to the KEMET relay. 5v coil, same form factor and contact arrangement, latching single coil type.

The relay consumes 100mw when active, meaning we're talking about a transient spike of 11.11ma at the coil itself. Not a whole lot, and we're talking about a little over half that on the 18v side...but again, since it's latching that current spike is only a blip.

You said that this only happens when you use the 18vdc power supply, right? Is that power supply chained to anything else?

Thanks for getting back with me. I chose the Kemet because the specs were practically identical and they are what's available. So I bought a lot, lol.

I've been messaging back and forth with the customer. Turns out he is using 3 different power supplies for his board. The one with an 18v output is a cheap one from Amazon. Looking at that power supply, it doesn't have a lot of power and none of the outputs appear to be truly isolated. He was trying to use a digital impulse response loader style pedal with analog pedals on a power supply that doesn't have isolated outputs. Big no-no! So first, he didn't have enough power for everything he wanted and second, digital and analog on same power source creates all kinds of noise. He didn't know that. So we had a clean power discussion and his next purchase is a serious power supply. He did however have a music shop test the power consumption at 19ma.

This is the second customer saying it's the pedal (both using relay bypass latching) but it's turned out being their power supplies. Glad to know the products are good!

Thanks again for your quick replies guys I really appreciate it.

 

[thesoundofjusticefx]

Looking at the data sheet this relay looks compatible with this build even though a TQ2-L-5V is recommended (and impossible to get hold of).

Did you test the pedal without the relay board attached to narrow it down to see if it definitely is the relay board or main PCB?

Can you post some clear pictures of the board when you get the pedal back.

Thanks for getting back with me. I chose the Kemet because the specs were practically identical and they are what's available. So I bought a lot, lol.

And thanks, I do test each part separately then all at once. I have a pretty thorough test procedure cuz I have no idea how the person receiving my pedals are gonna treat them. Some people are just rough on their stuff, lol.

I've been messaging back and forth with the customer. Turns out he is using 3 different power supplies for his board. The one with an 18v output is a cheap one from Amazon. Looking at that power supply, it doesn't have a lot of power and none of the outputs appear to be truly isolated. He was trying to use a digital impulse response loader style pedal with analog pedals on a power supply that doesn't have isolated outputs. Big no-no! So first, he didn't have enough power for everything he wanted and second, digital and analog on same power source creates all kinds of noise. He didn't know that. So we had a clean power discussion and his next purchase is a serious power supply. He did however have a music shop test the power consumption at 19ma.

This is the second customer saying it's the pedal (both using relay bypass latching) but it's turned out being their power supplies. Glad to know the products are good!

Thanks again for your quick replies guys I really appreciate it.