PeachParts Mercedes-Benz Forum - View Single Post

Jeremy5848 · #2 06-26-2006, 01:19 AM

One source is Mouser Electronics. See their catalog at http://www.mouser.com/catalog/626/1367.pdf. The Omron H3CR-A SERIES: 1/16 DIN, ANALOG-SET, SOLID-STATE TIMER ($62.25 each) is available to operate on 12 Volts DC. It will handle a maximum of 5 Amps so you would have to use a relay to handle your 30 Amp load. For that great a load, it would be wise to use a capacitor or other supressive element across the load terminals or the inductive kick from the motor, when the power is turned off, will cause arcing across the contacts and will destroy them in a short time.

There are probably industrial delay timers that would handle such a load directly but they would be much larger, would be unlikely to operate from 12 Volts DC, and would be much more expensive.

There are also timers available in the surplus market that might do what you want, with or without an external relay to handle the load. Meeting your exact requirements (12 Volt DC operation, time delay of a couple of seconds, 30 Amp load) would be difficult.

Another possibility would be a pure delay circuit (instead of a more generic timer circuit), which could be built from a capacitor, a transistor, and a couple of resistors. That circuit could then actuate a relay to switch the 30 Amp load. You would have to build such a device yourself or find a technician to do it for you. You might be able to find such a person by asking at a local electronics shop in your area; such a place might stock a timer that would do what you want.