Derringer II LED output voltage
Printed From: the12volt.com
Forum Name: Car Security and Convenience
Forum Discription: Car Alarms, Keyless Entries, Remote Starters, Immobilizer Bypasses, Sensors, Door Locks, Window Modules, Heated Mirrors, Heated Seats, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=24504
Printed Date: November 15, 2025 at 6:04 PM
Topic: Derringer II LED output voltage
Posted By: yoda888
Subject: Derringer II LED output voltage
Date Posted: January 13, 2004 at 11:54 AM
Hey all, This question is in regards to an old school alarm. A Derringer II made by now out-of-business VSE. I'm going to swap the alarm out and put in a Crimestopper alarm. Just something basic (door locks and flashing lights), nothing fancy. However, there are currently 3 LEDs from the Derringer alarm. I'd like to keep those 3 LEDs if at all possible. My question then is: What is the voltage output for the LED out of the Derringer alarm? (if no one knows, how can I test for this voltage output?) Thanks!
Replies:
Posted By: Teken
Date Posted: January 13, 2004 at 4:41 PM
The quickest method is to simply remove the LEDs from the alarm, then measure the voltage from the alarms LED output driver.
Regards
EVIL Teken . . .
Posted By: yoda888
Date Posted: January 13, 2004 at 6:17 PM
Teken, Thanks for the response. The Derringer doesn't work that great right now. Hence the reason for changing alarm systems. I can't really get a voltage reading from the current LED out, because I can't arm the alarm!  So, if someone happens to have the voltage knowledge that would be great! Thanks! Teken] wrote:
he quickest method is to simply remove the LEDs from the alarm, then measure the voltage from the alarms LED output driver.
Regards
EVIL Teken . . .
Posted By: yoda888
Date Posted: January 14, 2004 at 12:42 PM
Anyone? Help? Please? 
Posted By: Teken
Date Posted: January 14, 2004 at 3:35 PM
If you want to play it safe and do not know if this LED is a 12 volt version. Then simply place a 470 ohm resistor in series with the LED from the Derringer II.
This will limit the amount of current that will pass through the 3 LED's.
Upon power up, if the LED's appear to be too dim, then remove the resistor. That will either restore the amount of light output, or melt the LED's within a few minutes...
Regards
EVIL Teken . . .
Posted By: yoda888
Date Posted: January 14, 2004 at 4:58 PM
Teken, Thanks for the info. A couple of more questions. 1. Which way is which on the resistor? You said put it inline with the LEDs. I assume it goes on the positive wire. But is there a "direction" the resistor goes? 2. What resistence should I use if the output of the AlarmBrain is 3volts? 3. What are the "popular" LED output voltages for alarms? 12v? 3v? 2v? I like your idea of seeing if the LED is dim. If it's dim that means it's not 12v. The LED output from my NEW alarmbrain will be 3v. I just want to make sure I don't have 2v LEDs in there currrently. Thanks!
Posted By: Teken
Date Posted: January 14, 2004 at 7:25 PM
yoda888 wrote:
Which way is which on the resistor?
The resistor can be placed in any direction. You will need a 1/4 watt resistor.
yoda888 wrote:
I assume it goes on the positive wire.
Yes . . .
yoda888 wrote:
AlarmBrain is 3volts?
You would not require a resistor if it is 2-3 volts.
yoda888 wrote:
What are the "popular" LED output voltages for alarms? 12v? 3v? 2v?
All three voltages are being used. The major alarm manufactors do use 2-3 volts as the output driver.
yoda888 wrote:
I like your idea of seeing if the LED is dim. If it's dim that means it's not 12v. The LED output from my NEW alarmbrain will be 3v. I just want to make sure I don't have 2v LEDs in there currrently.
The above method is very much the last resort, and is the *Shade Tree* mechanic way to do it, but is not the ideal or safe way.
Technically speaking, you will want to know what the maximum current the LED can sustain. Typically speaking for a standard red LED it is 20 mA. So if it is a 2 volt LED and your alarm driver is 3 volts, then you will have to drop down 1 volt through a resistor.
Which will be a 50 ohm resistor at 1/4 watts.
Regards
EVIL Teken . . .
Posted By: bmf1000d
Date Posted: January 14, 2004 at 8:22 PM
Man i have not seen that name in a LONG time. Not i would go with what teken said but if i remeber corectly its 3 volts if it is a Derringer II and not a Derringer IIv2. the other was an updated model with more built in relays.
-------------
"Big" Mike
Double Take
Fremont, Ne
remember to check all your wires with a dmm not a test light!!
i take no responsibilty whatsoever for the vailidty of the info nor consequences thereof
Posted By: yoda888
Date Posted: January 14, 2004 at 9:28 PM
Dumb question. I ASSume I can just look on the brain to see which version of the alarm I have (I thought I'd ask first before I rip it out and work half way thru and then post and wait for a response). Will the brain say DerringerII v2? or will it say DerringerII and I gotta guess? This alarm is circa '94, so I have a funny feeling it might be the "newer v2" version.  But I can always hope!  bmf1000d wrote:
Man i have not seen that name in a LONG time. Not i would go with what teken said but if i remeber corectly its 3 volts if it is a Derringer II and not a Derringer IIv2. the other was an updated model with more built in relays.
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