<div dir="ltr">I LM317 is a voltage regulator. You CAN use it as you describe, basically with a series resistor to sink the excess voltage and therefore indirectly adjust drive current. But I find this approach to have a very poor dimming curve. The PWM dimming solution gives you a much better control, especially at the dim end of the curve. The other issue with the LM317 is that it is not very efficient. All the gains you get from going to LEDs are essentially going to be lost as heat from the regulator.<br></div><div class="gmail_extra"><br><div class="gmail_quote">On Wed, Feb 21, 2018 at 4:50 PM, Paul Tegler <span dir="ltr"><<a href="mailto:ptegler@verizon.net" target="_blank">ptegler@verizon.net</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Randal corrected my 'incomplete' response (tnx)<br>
see below<br>
<br>
all my LBC's have LED's in the dash<br>
since they draw much less current than normal bulbs all you need is a<br>
simple LM317 regulator,<br>
one 5K pot and one 240 ohm resistor<br>
<br>
It will be 'warn to the touch, but no more than the old bulbs would be warm<br>
<br>
look up the spec sheet for am LM317. truly dirt simple...doesn't need and diodes or caps<br>
<br>
ptegler<br>
<br>
Paul Tegler <a href="mailto:ptegler@verizon.net" target="_blank">ptegler@verizon.net</a> <a href="http://www.teglerizer.com" rel="noreferrer" target="_blank">www.teglerizer.com</a><div><div class="h5"><br>
<br>
On 2/21/2018 12:35 PM, Randall wrote:<br>
</div></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div class="h5"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
One note of caution. Read the instructions that come with a PWM dimmer<br>
carefully. Some require that the LED's connected to them are NOT<br>
</blockquote>
grounded.<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
This can be a real pain the butt for LBC's where everything is metal and<br>
all the metal is grounded.<br>
</blockquote>
Which is exactly why I would say the one you linked to is Not Suitable.<br>
<br>
As usual, Amazon won't tell you little things like whether you can use it or<br>
not; but the information is on the seller's web site:<br>
<br>
"As with pretty much all dimmer switches, the ground side is switched rather<br>
than the positive side. So you must hookup the output ground wire to your<br>
LEDs."<br>
<br>
<a href="https://www.oznium.com/led-dimmer-knob" rel="noreferrer" target="_blank">https://www.oznium.com/led-dim<wbr>mer-knob</a><br>
<br>
-- Randall<br>
<br>
<br></div></div><span class="">
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