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chaskuss(at)yahoo.com
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 Posted: Sun Mar 22, 2020 3:17 am Post subject: AeroElectric-List Digest: 2 Msgs - 03 |
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Tim, LEDs operate on 3 volts or less. You cannot Supply an LED with more than 5 volts at the very maximum. Generally you have to install a resistor in the circuit to drop the voltage down to a safe level for the LED. Bottom line is you've probably destroyed that LED.
Charlie
Sent from Yahoo Mail on Android
| Quote: | On Sun, Mar 22, 2020 at 1:50 AM, Tim Jennings
<tjennings07(at)gmail.com> wrote:
| Quote: | | Hello. I have a SB1B-14 https://bandc.com/product/standby-alternator-controller-14v-homebuilt/ installed in my plane and previously used the supplied 12 volt incandescent bulb as the annunciator. I recently cut a new panel and installed a 12 volt LED bulb in place of the incandescent one. For some reason the led does not light up. There was 11.8 volts at the led bulb but it would not light up. On the bench power supply it lights up well below 10 volts. Per the SB1B-14 product details "Note: low-voltage monitoring and warning system designed for use with an incandescent lamp (supplied) only.". Is there a simple way to make this work utilizing my led bulb on the panel? Maybe wire the led bulb in series with the "hidden and out of sight" incandescent bulb behind the panel? Thanks for your input. |
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- Tim Jennings
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ashleysc(at)broadstripe.n
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| Posted: Sun Mar 22, 2020 6:21 am Post subject: AeroElectric-List Digest: 2 Msgs - 03 |
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Hi Tim and Charlie;
It's a complicated world out there. I have an LED that works on 12 volts. Don't know how that's accomplished, but Charlie has a good point. Need to find the intended voltage.
Cheers! Stu.
From: "Charles Kuss" <chaskuss(at)yahoo.com>
To: aeroelectric-list(at)matronics.com
Sent: Sunday, March 22, 2020 4:14:55 AM
Subject: Re: Re: AeroElectric-List Digest: 2 Msgs - 03
Tim, LEDs operate on 3 volts or less. You cannot Supply an LED with more than 5 volts at the very maximum. Generally you have to install a resistor in the circuit to drop the voltage down to a safe level for the LED. Bottom line is you've probably destroyed that LED.
Charlie
Sent from Yahoo Mail on Android
| Quote: | On Sun, Mar 22, 2020 at 1:50 AM, Tim Jennings
<tjennings07(at)gmail.com> wrote:
| Quote: | | Hello. I have a SB1B-14 https://bandc.com/product/standby-alternator-controller-14v-homebuilt/ installed in my plane and previously used the supplied 12 volt incandescent bulb as the annunciator. I recently cut a new panel and installed a 12 volt LED bulb in place of the incandescent one. For some reason the led does not light up. There was 11.8 volts at the led bulb but it would not light up. On the bench power supply it lights up well below 10 volts. Per the SB1B-14 product details "Note: low-voltage monitoring and warning system designed for use with an incandescent lamp (supplied) only.". Is there a simple way to make this work utilizing my led bulb on the panel? Maybe wire the led bulb in series with the "hidden and out of sight" incandescent bulb behind the panel? Thanks for your input. |
--
- Tim Jennings
|
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?AeroElectric-List |
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ashleysc(at)broadstripe.n
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| Posted: Sun Mar 22, 2020 8:17 am Post subject: AeroElectric-List Digest: 2 Msgs - 03 |
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Hi Dick;
As you explain, my (red) LED must have a resistor in series.
My other point was that mine had a pos. and neg. connection and wouldn't work if hooked up backwards.
Cheers! Stu.
From: "Dick Tasker" <dick(at)thetaskerfamily.com>
To: aeroelectric-list(at)matronics.com
Sent: Sunday, March 22, 2020 8:46:48 AM
Subject: Re: Re: AeroElectric-List Digest: 2 Msgs - 03
If you have an LED that works on 12V then it is an assembly that includes a resistor in series with the actual LED. These can be designed for any arbitrary voltage that is more than the minimum for the LED which is between 1.8 and 3.3 volts depending on the LED color. Just choose a resistor that limits the LED current to less than the maximum rating at the desired voltage. For instance, with a red LED, which runs drops 1.8V designed for a 10mA current would use a ohm resistor. (V/I = R : (12-1. /.01 = 666 ohms) Of course resistors come in discrete values so in this case you would probably use a 680 ohm resistor. One would also have to calculate the power rating required for the resistor. (V*I = P : (12-1./.01 = 0.102). In this case just about any resistor you can buy will work, but to be safe use a 1/4 watt rated resistor.
I may be wrong, but I seem to remember reading somewhere that the scheme you want to use works if you put a resistor in parallel with the 12V LED that simulates the load that the incandescent light provides to the circuit. For instance if it is a 2W light running from 12V you would use a 75 ohm resistor rated at for least 2W. (V*V/P = R : 12 * 12/2 = 72 ohms) You could also probably get away with a higher value resistor as well. Experiment.
Dick Tasker
ashleysc(at)broadstripe.net (ashleysc(at)broadstripe.net) wrote:
| Quote: | Hi Tim and Charlie;
It's a complicated world out there. I have an LED that works on 12 volts. Don't know how that's accomplished, but Charlie has a good point. Need to find the intended voltage.
Cheers! Stu.
From: "Charles Kuss" <chaskuss(at)yahoo.com> (chaskuss(at)yahoo.com)
To: aeroelectric-list(at)matronics.com (aeroelectric-list(at)matronics.com)
Sent: Sunday, March 22, 2020 4:14:55 AM
Subject: Re: Re: AeroElectric-List Digest: 2 Msgs - 03
Tim, LEDs operate on 3 volts or less. You cannot Supply an LED with more than 5 volts at the very maximum. Generally you have to install a resistor in the circuit to drop the voltage down to a safe level for the LED. Bottom line is you've probably destroyed that LED.
Charlie
Sent from Yahoo Mail on Android
| Quote: | On Sun, Mar 22, 2020 at 1:50 AM, Tim Jennings
<tjennings07(at)gmail.com> (tjennings07(at)gmail.com) wrote:
| Quote: | | Hello. I have a SB1B-14 https://bandc.com/product/standby-alternator-controller-14v-homebuilt/ installed in my plane and previously used the supplied 12 volt incandescent bulb as the annunciator. I recently cut a new panel and installed a 12 volt LED bulb in place of the incandescent one. For some reason the led does not light up. There was 11.8 volts at the led bulb but it would not light up. On the bench power supply it lights up well below 10 volts. Per the SB1B-14 product details "Note: low-voltage monitoring and warning system designed for use with an incandescent lamp (supplied) only.". Is there a simple way to make this work utilizing my led bulb on the panel? Maybe wire the led bulb in series with the "hidden and out of sight" incandescent bulb behind the panel? Thanks for your input. |
--
- Tim Jennings
|
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| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?AeroElectric-List |
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