delay startup circuit or device
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Forum Name: Relays
Forum Discription: Relay Diagrams, SPDT Relays, SPST Relays, DPDT Relays, Latching Relays, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=121489
Printed Date: June 11, 2024 at 12:17 AM
Topic: delay startup circuit or device
Posted By: crankycowboy
Subject: delay startup circuit or device
Date Posted: April 24, 2010 at 10:07 AM
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!
Replies:
Posted By: oldspark
Date Posted: April 24, 2010 at 11:49 AM
Use a 12V relay instead of a transistor.
Posted By: howie ll
Date Posted: April 24, 2010 at 12:10 PM
Or a 528t set to about 3 secs.
Posted By: crankycowboy
Date Posted: April 24, 2010 at 5:02 PM
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?
Posted By: crankycowboy
Date Posted: April 24, 2010 at 5:04 PM
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
Posted By: KPierson
Date Posted: April 24, 2010 at 5:20 PM
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
Posted By: oldspark
Date Posted: April 24, 2010 at 7:46 PM
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.)
Posted By: crankycowboy
Date Posted: April 24, 2010 at 8:30 PM
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.
Posted By: crankycowboy
Date Posted: April 24, 2010 at 8:33 PM
KPierson wrote:
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.
Can you please explain in more detail where the diode goes and how to wire that up? Sorry
Posted By: i am an idiot
Date Posted: April 24, 2010 at 10:12 PM
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.
Posted By: crankycowboy
Date Posted: April 24, 2010 at 10:19 PM
i am an idiot wrote:
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.
Yes, the amp turn on lead, works as it's supposed to in terms of timing. Unfortunately, when I connect a load to it, the voltage drops substantially and won't trigger my amps. If you have a solution, I would be GREATLY appreciative!
Posted By: i am an idiot
Date Posted: April 24, 2010 at 10:57 PM
Tip3055 transistor availabe from radio shack. Output of your amp remote terminal of your carPC to the base (left leg) of the transistor. Constant 12 volt feed to the collector (center leg, or the metal tab of the transistor) Connect the remote terminals of the amps to the emitter (right leg) of the transistor. The metal tab of the transistor will have 12 volts on it. You must insulate it somehow. A piece of 3/8 inch heat shrink tubing will slide over it and keep it from touching anything.
Posted By: KPierson
Date Posted: April 24, 2010 at 11:00 PM
Simple NPN relay drive circuit: 
If you are going to use a resistor on the base I would use a 470 instead of a 10K. It is not required but recomended. The common contact on the relay (pin 30) would connect to 12vdc and the NO output (pin 87) would be your output. ------------- Kevin Pierson
Posted By: crankycowboy
Date Posted: April 25, 2010 at 7:59 AM
KPierson wrote:
Simple NPN relay drive circuit:
If you are going to use a resistor on the base I would use a 470 instead of a 10K. It is not required but recomended. The common contact on the relay (pin 30) would connect to 12vdc and the NO output (pin 87) would be your output.
Thanks Kevin. I am about to make my ignorance very apparent here. I'm really not good at reading schematics. Do you mind giving a brief explanation in laymans (dumb ***) terms? Once again I apologize for being a pain...I just want to make sure I understand completely. Thanks again.
Posted By: dualsport
Date Posted: May 17, 2010 at 7:28 AM
If you connect up an ammeter from your 12V supply to your remote turn on input of your Rockford amp, what do you measure?
Posted By: anonymous1
Date Posted: May 17, 2010 at 9:29 AM
What PSU on earth cant pull in a relay at 12v? Either something is wrong with the way you measure the voltage or the PSU is not your solution and you need to follow the posts from oldspark and howie II on the first page. No offense but I think you need an all-n-one solution to your problem. (I would) Buy the dei part or any relay with variable timing and skip the psu all together. ------------- I know just enough to be dangerous. VERY dangerous.
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