SPDT relay
05-13-2010, 06:57 AM
#1
SPDT relay
At what point should you install a spdt relay for the remote wire. Seems like we may have too much for the poor little Panasonic deck.
Remotes are needed to - 3 amps, indash eq, hybrid cap and 2 or 3 line drivers.
Too much for the deck remote?
I know they're cheap as dirt those relays, just wondering if I should add one or not.
Remotes are needed to - 3 amps, indash eq, hybrid cap and 2 or 3 line drivers.
Too much for the deck remote?
I know they're cheap as dirt those relays, just wondering if I should add one or not.
05-13-2010, 04:12 PM
#5
500 Watt CAFz'r
Join Date: Apr 2006
Posts: 633
Unplug your remote wire and set your DMM to milliamps - put one probe on positive and then your negative to where the remote wire goes... this should show you how much current it takes to turn on each device... should be low, though I have heard there being some amps out there that do take more amperage to fire up try it out
05-26-2010, 09:20 PM
#7
50 Watt CAFz'r
Join Date: Mar 2006
Posts: 50
I still like using a 2N6387 or TIP120 to make my turn-on "relay". All it takes is one of the transistors mentioned, a 1Kohm resistor in series on the base, and a 100kohm resistor parallel with the emitter and ground.
From left to right, with the transistor facing you and the tab (part with the mounting hole) up, you have three legs on the transistor; base, collector and emitter.
The 1kohm resistor goes on the base. This is where you connect the remote lead coming from your head unit. The collector, (leg in the middle) gets an ignition switched 12V lead that can provide enough current to turn on your devices (like the #30 tab on a bosch relay), of course, you fuse the input to the collector!!!!!
The emitter goes to your devices that need the 12V turn-on. A 100Kohm resistor is connected from the emitter to ground.
The tab of the transistor must be isolated from touching ground. You can mount everything on a really small piece of perf board then lead out the wires and cover the whole thing with some heat-shrink tubing. The parts are inexpensive and the big benefit is the lack of relay "pop" that can occur with electromechanical switches.
I usually put together a dozen of these little assemblies so that they're on hand and ready for use in my shop. They're perfectly capable of providing enough current for turning on components. If you attach a small heat-sink to the 2N6387, it can dissipate up to 10A.
I save the relays for stuff that demands higher current.
Will try to remember to photograph an assembly next time I put some together.
From left to right, with the transistor facing you and the tab (part with the mounting hole) up, you have three legs on the transistor; base, collector and emitter.
The 1kohm resistor goes on the base. This is where you connect the remote lead coming from your head unit. The collector, (leg in the middle) gets an ignition switched 12V lead that can provide enough current to turn on your devices (like the #30 tab on a bosch relay), of course, you fuse the input to the collector!!!!!
The emitter goes to your devices that need the 12V turn-on. A 100Kohm resistor is connected from the emitter to ground.
The tab of the transistor must be isolated from touching ground. You can mount everything on a really small piece of perf board then lead out the wires and cover the whole thing with some heat-shrink tubing. The parts are inexpensive and the big benefit is the lack of relay "pop" that can occur with electromechanical switches.
I usually put together a dozen of these little assemblies so that they're on hand and ready for use in my shop. They're perfectly capable of providing enough current for turning on components. If you attach a small heat-sink to the 2N6387, it can dissipate up to 10A.
I save the relays for stuff that demands higher current.
Will try to remember to photograph an assembly next time I put some together.
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