Outputs don't have enough power to push relays

**PaulF** · 06-22-2009, 05:54 PM

I have a new Fusion Brain V4 which I bought in February. Today is the first day I've actually tried to use it. I have a battery on my test bench which I'm using to supply the fusion brain its power. The voltage at the battery is 12.2 volts right now. When I turn on an output on the fusion brain and test it with the same volt meter I get 11.52 volts. When I plug in a relay to that output, the relay does click but it also hums and then sporadically clicks back and forth quickly. With a relay plugged in, if I hook up the volt meter in parallel with the relay, I get 7-8 volts. Unplug the relay and I'm back up at 11.52. The relay works perfectly fine when it is connected directly to the battery. I even tested its current draw and got 81.2 milliamps which is well within the specs of the fusion brain. Why is power having such a hard time reaching the outputs?

**chunkyks** · 06-22-2009, 06:59 PM

<blather about transistors>

Please ignore this post, it has no useful purpose other than to confuse the issue.

Gary (-;

**malcom2073** · 06-22-2009, 07:12 PM

Hey Paul: What relay are you using? Did you get it from the FB guys, if so what's the part number?

Also, do you have the FB's power jumper set to external?

**PaulF** · 06-22-2009, 07:39 PM

Originally Posted by malcom2073

If the output is coming directly out of a regular logic chip, you can't usually rely on it working a coil. This is exactly the problem that transistors solve; you can either use a beefy transistor in place of the relay you're trying to use, or you can use less beefy transistor to drive the relay.

Which one you use depends on what you're doing on the other side of the relay. Starter motor, drive a relay with a transistor. Most other things, just use a transistor.

Gary (-;

The outputs on the Fusion Brain are designed to run relays. Their website even sells relays with the connectors that connect the relays right to the pins on the board in a matter of 3 seconds.

Originally Posted by malcom2073

Hey Paul: What relay are you using? Did you get it from the FB guys, if so what's the part number?

Yes I ordered it from the FB guys. It's made by Potter & Brumfield
The model is T9AS5D22-12

Originally Posted by malcom2073

Also, do you have the FB's power jumper set to external?

That's my jumper configuration, which I believe is correct.

**malcom2073** · 06-22-2009, 07:43 PM

Well those were the only two questions I had, I'm out of ideas :-/. 81mA is indeed well within the limit of the chips the FB uses, so that shouldn't be an issue.

It's not possible you're accidentally pwming the output is there? That's about the only thing I can think of that would cause such a drop like that (and therfore reducing the amount of voltage both your multimeter and the relay would see)

**PaulF** · 06-22-2009, 08:00 PM

Unless the Fusion Brain linux program is mistakenly PWMing it, I doubt it's that.
It seems like there is just some huge resistance happening within the board.

Also, I tried plugging in a tiny fan which requires .1 amps and the fan does run, but what is weird is the led lights from 2-8 came on dimly, and the led light for 1 stayed on normally.

When I plug in the relay, whenever it sporadically clicks, the LED light also flickers and the voltage drops down a bit. The input voltage from the power supply doesn't change at all though.

**Curiosity** · 06-22-2009, 08:07 PM

Relay humming? Double check that PWM.

I don't think all the outputs are PWM so try others.

**2k1Toaster** · 06-22-2009, 08:11 PM

Just to clear things up, the Fusion Brain is designed to directly drive a relay. So disregard post #2 completely.

Are you just trying to power the 1 relay, or lots at the same time? Have you tried a different output? It could be that one is fried. If so we will replace it for you.

The jumper configuration is correct to power it from an external source.

Is there a way you can try to power it from a power supply instead of a battery? Just to try and rule out other possibilities.

**PaulF** · 06-22-2009, 08:45 PM

I've powered it off three different sources with the same results:
A desktop PSU, a wall wart, and the battery. The battery is the most powerful option available with the highest voltage. I figured maybe the brain wouldn't operate under 12 volts and the desktop PSU was at 11.9 and the wall wary was 11.7.

I've tried it on both connectors 1 and 2. I'll try to see if I can get it running on a windows box if PWM is really a possible problem. It wouldn't be the first bug in the linux application...

**Iamthehor** · 06-23-2009, 03:01 PM

Is this one of the mysterious 24V relays? the -12 on the p/n leads me to believe otherwise, but you never know if it was stenciled wrong. will the relay throw when you put 12V to it? (connect coils directly to the battery)

Also, I thought PWM wasn't implemented in firmware yet? unless the linux program is utilizing a flux capacitor......