Quick Mesa connection question...

Hey guys,

Very close to getting things run on my machine but before I start pulling wires I wanted to ask about flyback diodes for use with relays on the outputs of the Mesa 7i76/7 cards, are they needed? If so, can anyone link to what exactly I would need to use? I've never used a flyback diode before, not sure if there's a certain type required for the board if they are needed.

Below is the schematic I made for wiring everything on the machine, I if you guys have a minute to run eyes over it and make sure I'm not goofing anywhere obvious it would be much appreciated!

Thanks guys!!

Chris

Yes, I've seen PCW mention this. The band on the diode should point towards the output on the board.

Any diode would pretty much do as long as it can handle 24 volts or whatever field power you are using.

tommylight wrote:

Do use the diodes always, even if you have low current relays.
As soon as someone switches one of them on and off fast, the output will fail for sure.
Use them as Rod explained, solder them to the relay contacts or terminals.

Been researching it all morning, being a bit overwhelmed by my research, I decided it best to order new icecube relays from Fuji which have the correct surge suppression in the relay already, man they are proud of them but better safe than sorry. Need like 13 of them at $13 piece plus shipping. I was getting so many conflicting points of view on diode sizing saying to big and it will weld the coil contacts closed and to small will burn the diode up which would hurt the Mesa card.. seemed like such a fine line to walk and then they said I needed to measure my coil with an oscope to determine the correct size and should use a zener diode instead... My head is spinning now.. Fuji offers relays with diode suppression or CR? Suppression..

HH52P-FL is the relay with built in diode suppression

HH52P-CRL is the relay with built in CR suppression



Chris

Lcvette wrote:

tommylight wrote:

Do use the diodes always, even if you have low current relays.
As soon as someone switches one of them on and off fast, the output will fail for sure.
Use them as Rod explained, solder them to the relay contacts or terminals.

Been researching it all morning, being a bit overwhelmed by my research, I decided it best to order new icecube relays from Fuji which have the correct surge suppression in the relay already, man they are proud of them but better safe than sorry. Need like 13 of them at $13 piece plus shipping. I was getting so many conflicting points of view on diode sizing saying to big and it will weld the coil contacts closed and to small will burn the diode up which would hurt the Mesa card.. seemed like such a fine line to walk and then they said I needed to measure my coil with an oscope to determine the correct size and should use a zener diode instead... My head is spinning now.. Fuji offers relays with diode suppression or CR? Suppression..

HH52P-FL is the relay with built in diode suppression

HH52P-CRL is the relay with built in CR suppression


Chris

Those will work along with most any diode. I usually use 4001's. This is so when the relay releases spike don't get sent back into the mesa board.

NOTE: This won't do much for spikes coming through the contacts of the relay though. Really depends what you are switching with the relays.

BTEW Those relays you show with built in diodes will work just fine. Dont sweat it.

bevins wrote:

Lcvette wrote:

tommylight wrote:

Do use the diodes always, even if you have low current relays.
As soon as someone switches one of them on and off fast, the output will fail for sure.
Use them as Rod explained, solder them to the relay contacts or terminals.

Been researching it all morning, being a bit overwhelmed by my research, I decided it best to order new icecube relays from Fuji which have the correct surge suppression in the relay already, man they are proud of them but better safe than sorry. Need like 13 of them at $13 piece plus shipping. I was getting so many conflicting points of view on diode sizing saying to big and it will weld the coil contacts closed and to small will burn the diode up which would hurt the Mesa card.. seemed like such a fine line to walk and then they said I needed to measure my coil with an oscope to determine the correct size and should use a zener diode instead... My head is spinning now.. Fuji offers relays with diode suppression or CR? Suppression..

HH52P-FL is the relay with built in diode suppression

HH52P-CRL is the relay with built in CR suppression


Chris

Those will work along with most any diode. I usually use 4001's. This is so when the relay releases spike don't get sent back into the mesa board.

NOTE: This won't do much for spikes coming through the contacts of the relay though. Really depends what you are switching with the relays.

BTEW Those relays you show with built in diodes will work just fine. Dont sweat it.

Bevins,

You mean the 1N4001's? i was thinking about diodes and remembered i had bought a kit a while back with lots of various resistors and transistors etc.. and low and behold it had a pack labeled diodes in it.. see picture for what it had in there... if you guys think any of these would work? maybe i would give it a go! watched a youtube video of how to pop the cap of the icecube relays and solder them right on the coil posts an clip the excess and pop the cover back on.. looked easy enough! i was just worried with which diodes to use..

thanks.. doesn't look like i have the 1N4001's Bevins but i can always order them if those are the correct ones! I have 1N4007

Almost any silicon diode will work
its very unpicky ( your IN4001, 1N4007, 1N4148, FR107, FR207 are all fine)

You dont need diodes for most low power relays since the output driver circuits have built in flyback suppression
But above 50-60 mA, I would suggest using a flyback diode.

output suppression (across the contacts) depends on the load
(AC typically uses RC snubbers DC typically uses flyback diodes across the relays load)

PCW wrote:

Almost any silicon diode will work
its very unpicky ( your IN4001, 1N4007, 1N4148, FR107, FR207 are all fine)

You dont need diodes for most low power relays since the output driver circuits have built in flyback suppression
But above 50-60 mA, I would suggest using a flyback diode.

output suppression (across the contacts) depends on the load
(AC typically uses RC snubbers DC typically uses flyback diodes across the relays load)

cool... I will put them on just to be safe... i'm not certain what the milliamp draw is on the relays. the rest of the connected items i think are quite low and should be under that threshold. I did a practice relay by popping the cover off and soldering the diode across the coil posts with the striped side on the negative coil post side as i read to do and it went pretty easy. was harder popping the cover off the first time than soldering the diode on..lol then two snips and pop the cover back on and check no internal contact anywhere it was supposed to be. triggered the relay to make sure it functioned properly and it did so i'm guessing i did everything properly. phone died while in the shop but will post a picture of it tomorrow once i'm back out there!

Thanks again guys!

Chris!

Hi, I need to drive a relay with an output of my Mesa 7i96, and I have laying around a bunch of MIC UF4007. I see that they are specific for rectifying ac courrent. Can they also be used as flyback diodes in this case?
Thank you