Footswitch w/ LED for Rane RPM Remote

Chris BT Davis

Chris BT Davis

Freshman
Mar 6, 2011
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I'm planning to tackle building a footswitch for a Rane RPM44. The aim is to use the 5VDC logic and latching switches to mute/unmute different processing paths, like a guitar amp footswitch. The switch and software is all easy. But, I'd also like to have a status led with each switch: Circuit complete = LED on. This seems as simple as adding the LED & resistor on the back side of the switch and letting the logic voltage power the LED's. I don't have quite the electronics know-how to feel comfortable that there isn't something I'm missing. Any advice? Am I on the right track with this? Is there any concern that powering 2-3 LED's would cause enough sag to cause the logic relays to see <5VDC (100ma power supply)?

Apologies for the amatuerish question, but this is a little outside my normal scope. Thanks in advance for any help!
 
Re: Footswitch w/ LED for Rane RPM Remote

The VOP (Versatile Output Port) on the Rane can directly drive LEDs, and these VOP circuits can be programmed to activate as required. It'll take additional lines from the Rane to your footswitch, but it will also give more positive feedback of the Rane's status when making changes.

See page 5 of the RPM44 manual for more info.
 
Re: Footswitch w/ LED for Rane RPM Remote

Milt Hathaway said:
The VOP (Versatile Output Port) on the Rane can directly drive LEDs, and these VOP circuits can be programmed to activate as required. It'll take additional lines from the Rane to your footswitch, but it will also give more positive feedback of the Rane's status when making changes.

See page 5 of the RPM44 manual for more info.
Click to expand...

Thanks Milt. Using the VOP is the fallback plan, but since it doubles the number conductors to the footswitch I was hoping I might be able to get away with driving everything off of the VIP circuits.
 
Re: Footswitch w/ LED for Rane RPM Remote

What logic relays are you referring to? The VIPs themselves? It seems like their switching voltage is around 2.5v, so you have some room to sag. By latching switch, are you just referring to a mechanical switch that is non-momentary?

The potential success of this probably depends on the brightness you want out of the LEDs and how the Rane is limited to 100ma. If the supply current is limited by a resistor like how phantom power works, you may lose a lot of voltage from the 5v reference if you draw 40ma for a couple LEDs. If the supply has a flatter curve where you can get close to the 100ma out and still be near 5v, then you'll likely be fine.

You can experiment with a 1K linear pot and a multimeter or two to find the best series resistor value for your LEDs and watch the voltage/current results. I doubt you'll endanger your gear with a little experimenting.
 
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