How can I control 4 amps & a crossover from DSATX?

**Mears** · 06-13-2010, 02:12 PM

I have 4 amps and an electronic crossover in my truck, and I'm trying to figure out how I can use the aux_sw pin of the DSATX without exceeding it's current limits. I was originally planning on just using a bosch relay, but have since discovered that it's not capable of driving it. Is there any way to daisy chain relays where I have a the DSATX ground trigger a small relay that in turn +12v triggers a larger relay grounded directly to my vehicle's chassis?

**Mears** · 06-13-2010, 02:28 PM

Ok, I think I may have been confusing myself. As long as I pick a sufficient relay with a high enough coil resistance (e.g. http://www.radioshack.com/product/in...ductId=2062482) it shouldn't matter how much current is required to drive my amp's remote lines (as long as the switched +12v wire from the battery is of a suitable gauge), correct?

The only current following back across aux_sw should be the current required to energize the relay's coil. Do I have this right?

**CraziFuzzy** · 06-13-2010, 02:35 PM

yes, that's correct. That's really the point of a relay, to allow a small, low power device, to control a higher powered device.

**travi_21** · 06-13-2010, 03:32 PM

Correct. The +12v side of the relay coil will be connected to a 12v (fused) source (same source as 1 side of the relay contacts). The ground side of the relay coil will be connected to JP1 pin F1 on your DSATX.

The DSATX manual (http://www.octanium.com/dsatx.html) lists a max sink current of 50 ma into JP1 pin F1. The spec you'll want to look for when selecting a relay is the coil resistance. Select a relay with sufficient coil resistance to keep you below 50ma across the coil at around 15vdc (V=IR gives you a min coil resistance of 300 ohms).

I wouldn't worry much about wire gauge for driving the relay coil, or driving the amplifier switched inputs. Realistically, these are such small currents (both for relay coil, and amp switched inputs) you could get away with using some really small wire. Find yourself some stranded 20 ga wire and call it done (20 is a decent size for handling and such for a car install).