Help requested - Car horn relay

**cgarwood** · 09-20-2010, 07:37 PM

I have an old car that has been sitting in my yard for some time and gets decorated with lights for my Christmas show. It is near the porch where candy will be handed out. For my halloween display I would like to rig up a switch (either computerized or a manual pushbutton) that would make the headlights turn on and the horn honk. Headlights are not a problem, my father replaced them with regular lightbulbs I can run from my Ren24 or 595 controller. As for the horn, I have no idea how to rig that up. I have 2 Ren24s and an 80 channel Olsen 595 setup. I want something that can be triggered from outside of the car as I'll be roaming around the yard with a wireless mic and voice changer.

I can usually follow schematics but know nothing about making new circuitry. If anyone could help out please let me know.

Bonus points if I can control it with the computer and also have a manual pushbutton override.

Any help is greatly appreciated

**RichF** · 09-20-2010, 07:49 PM

Get a small 5v relay from RS and hook it up to your Olsen 595. YOu can do this with your headlights too

**Wombat** · 09-20-2010, 08:24 PM

can even use one of those DC relay boards from the parallel port

Wombat

**IdunBenhad** · 09-20-2010, 09:20 PM

Hi:
Normally, a car horn relay is activated by grounding one side of the relay coil. It is also 12vdc, as it operates from the battery.

Just make a connection to the horn relay with another set of relay contacts that go to ground and put a pushbutton in Parallel with the relay. Be sure you connect to the horn relays ground side. You can find the ground side by using a voltmeter and measuring from the relay coil connections to ground. Have someone press the horn ring and measure the voltage. The one that show NO voltage is the ground side. The other side will measure about 12 vdc

**Jrd** · 09-20-2010, 10:42 PM

That sounds like a fun and frightening project, maybe you can post a video of all this in action after Halloween.

**cgarwood** · 09-21-2010, 09:45 PM

I'll see what I can come up with. Getting ready to order a second 20,000cfm fog machine for the yard. Need to break out me Ren24s and double check the max amperage on the board. I'd like to add some 500watt halogen lights for lightning but don't want to overload my board

**txag2008** · 09-22-2010, 05:11 PM

Need to break out me Ren24s and double check the max amperage on the board. I'd like to add some 500watt halogen lights for lightning but don't want to overload my board

I wouldn't try to output a 500w light straight from your Ren24. 500watt=2.54A You usually don't want to go over 2A on a channel. The triacs and trace widths aren't designed to handle that much amperage.

**cgarwood** · 09-23-2010, 12:05 PM

That's what I was afraid of. Wouldn't 500 watts be closer to 4.5 amps? In the US, so its a 110VAC system, or is my math broken today? Both are possible!

Looking like I may not be able to use the 500watt halogens for it. I'm not sure my 595 relays can handle 5amps across an entire relay.

In other news, I have a second Hurricane 1300 fog machine on the way. I added a blog post last year with a few pics of my first Hurricane 1300 in action. Going to be interesting to see what my yard looks like with two of them going

**budude** · 09-23-2010, 01:01 PM

Originally Posted by cgarwood

That's what I was afraid of. Wouldn't 500 watts be closer to 4.5 amps? In the US, so its a 110VAC system, or is my math broken today? Both are possible!

Looking like I may not be able to use the 500watt halogens for it. I'm not sure my 595 relays can handle 5amps across an entire relay.

In other news, I have a second Hurricane 1300 fog machine on the way. I added a blog post last year with a few pics of my first Hurricane 1300 in action. Going to be interesting to see what my yard looks like with two of them going

You may want to just switch to a hockey puck style SSR (e.g. Crydom, Opto22) since they can usually handle high amps. I bought a Hurricane 1300 as well this year. I made a cooler out of a plastic bin and dryer vent tubing and then have a 20' section of irrigation hose going out of that. I fired it up (w/o the ice) and forgot the living room windows were open - my wife was not amused...

(worked great though :mrgreen

**cgarwood** · 09-23-2010, 01:10 PM

For the price, the 1300 just can't be beat. I won't even waste my money on small ones anymore. Just throw another 1300 (or maybe an 1100 i guess if you don't want 20,000cfm) into the mix. I ran it non-stop for 30 minutes last year when the wind picked up and it dumped fog out the entire time.

I think I'm going to try the irrigation hose method this year with one of my two machines. Could you maybe post some pics/video of the 1300 in action with the irrigation hose?