delay startup circuit or device

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crankycowboy

Member - Posts: 13

Joined: March 08, 2010

Location: Texas, United States

Posted: April 24, 2010 at 10:07 AM / IP Logged

I have a carpc which utilizes a dc/dc power supply. The power supply has a delay output that is meant to be used for the remote wire for your amp(s). Apparently rockford amps are more demanding (current) to latch on via the remote wire. The remote out of the PSU is 12v with no load, but only around 5 volts when connected to the amplifiers and it won't trigger (or crackle, or flicker or even hint that it is trying). I was told I could use a transistor and connect the collector or 12v constant, the base to the output wire of the PSU and the emitter out to the amps. I did this but it didn't work. I just need a variable delay triggered by the ignition wire so that I don't hear the aweful "POP" while the computer startsup or returns from hibernation. Will the DEI528t or the PAC tr-7 or one of david navones concoctions or something work for me? Any suggestions would be greatly appreciated!! Thanks in advance!

oldspark

Gold - Posts: 4,913

Joined: November 03, 2008

Location: Australia

Posted: April 24, 2010 at 11:49 AM / IP Logged

Use a 12V relay instead of a transistor.

howie ll

Pot Metal - Posts: 16,466

Joined: January 09, 2007

Location: United Kingdom

Posted: April 24, 2010 at 12:10 PM / IP Logged

Or a 528t set to about 3 secs.

crankycowboy

Member - Posts: 13

Joined: March 08, 2010

Location: Texas, United States

Posted: April 24, 2010 at 5:02 PM / IP Logged

That's the problem.....the delayed output on the PSU doesn't have enough current to latch a relay or turn on the amps....if it did, I wouldn't need anything. Therefore, I either need a semi-conductor of some sort that can up the amperage of the remote out on the PSU or a device that I can just use a POT to adjust a delay off the regular ignition wire. Any other suggestions?

crankycowboy

Member - Posts: 13

Joined: March 08, 2010

Location: Texas, United States

Posted: April 24, 2010 at 5:04 PM / IP Logged

Yeah, I would need more than 3 secs. as the delay has to be long enough that the sound card will intialize first so I don't get the "pop" upon startup or return from hibernation

KPierson

Platinum - Posts: 3,527

This member consistently provides reliable information

Joined: April 14, 2005

Location: Ohio, United States

Posted: April 24, 2010 at 5:20 PM / IP Logged

That won't work like that - transistors swap polarity.

Get a NPN transistor and hook the output up to the base. Hook the collector to to 12vdc and hook the emitter to the coil of a relay. You will need a diode across the coil of the relay to protect the transistor.

I have a feeling though that something is wrong with your unit. This may fix it, but there is no reason a remote turn on should require enough current to load down the output.

Kevin Pierson

oldspark

Gold - Posts: 4,913

Joined: November 03, 2008

Location: Australia

Posted: April 24, 2010 at 7:46 PM / IP Logged

And if the output does NOT have enough current to drive a relay etc, what is it intended to drive?

Originally you indicated it was the load that demanded too much - not a low rated output.

So what is the output capable of supplying or sinking, or what voltage & impedance is it?

And as KP said, a positive-On output would drive the Base of an NPN transistor though usually its Emitter goes to GND and its Collector to the hot connected relay or load. But either can work - the key is that the Base must be ~0.7V higher than the Emitter to turn on and allow current to flow into C & out E. (And the output current is limited to the transistor's gain times its Base current.)

crankycowboy

Member - Posts: 13

Joined: March 08, 2010

Location: Texas, United States

Posted: April 24, 2010 at 8:30 PM / IP Logged

I'm sorry guys. I don't have an extensive background in circuit design etc and my experience in that aspect of all of this is somewhat limited. The "amp out" on the power supply is meant to turn on an amplifier; however, I have heard that other's with my same amp model (rockford 300.1) have had the same problem. Initially, I had the amp out going to a relay that would trigger a couple fans to push/pull air in/out of the compartment I have my amps and carputer in....and also to turn on two amps. Assuming maybe it was too much of a draw, I tried connecting to only one amp....still nothing at all! Then I assumed maybe my unit was bad as was suggested. It was new, so I RA'd it for a new one. When the new one arrived I tried connecting only to one amp....still NOTHING (no light flicker, no sound, NOTHING). Then I did some research and read about trying a NPN transistor. I purchased a 2n4401 rated up to 800ma. I connected the collector to constant battery power, the base to the switch via the power supply line, and the emitter to the amps....and they still wouldn't come on. I didn't try connecting to a relay or by adding a diode. Some additional information; however, I measured voltage at the base and it was 12v....and at the collector....12v....but only like 2 volts on the emitter side. What the heck am I doing wrong? I'm just trying to get rid of the stupid amp pop....shouldn't be this hard......

Also, just want to say thanks to all you guys offering help! Greatly appreciated.

crankycowboy

Member - Posts: 13

Joined: March 08, 2010

Location: Texas, United States

Posted: April 24, 2010 at 8:33 PM / IP Logged

KPierson wrote:

Can you please explain in more detail where the diode goes and how to wire that up? Sorry

i am an idiot

Platinum - Posts: 13,670

Joined: September 21, 2006

Location: Louisiana, United States

Posted: April 24, 2010 at 10:12 PM / IP Logged

The connection intended for amp turn on, does it turn on at the correct time, meaning if I get it to power your amp up, do you still need the delay? This will be a simple one transistor fix. Just as the instructions you got from your original attempt. Transistor is available at Radio Shack. I am on a different computer and wil have to search this site for a diagram, give me a minute.

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