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Yes, but I like to follow the KISS school of design. Or as someone so famously said, "Make it a simple as possible, but no simpler".ikalogic said:An op-amp and a potentiometer will always give you more accurate results and easier control.
What are the resistor values you're using?osphoto said:In using the method that crutschow has described, my resistors are heating up.
I'm using 1w resistors.
I'm using a mock up with a 12v power supply at 1amp.
What can I do to cut down on the extreme heat these resistors are putting off? Extreme heat being to hot to touch.
I assume it's just the 200 ohm resistor that's heating up since it would take over 100mA to heat up the 22 ohm resistor and that's a lot of current to be running through the LED which will shorten its life. If it is getting hot you may need to increase its value. You can determine the LED current by measuring the voltage accros the resistor and using ohm's law (I = V/R).osphoto said:Resistors Value
1 Watt @ 200 Ohms
Which is parallel To:
Series: Diod + Diod (12 V rated diods) + LED + 1 watt @ 22 Ohms
This will start to heat up after about 3 to 4 minutes. And it gets hotter the longer I leave the power on.
crutschow said:Incidently, resistors normally get hot when dissipating their rated power.
A typical battery voltage when an engine is charging is around 14V so you may want the check your circuit with that voltage.osphoto said:I also need to verify my power source on the actual device that this is going to be used at. Like the Amps.
osphoto said:Cheap welder? That sounds like a voice of experience.
I wont get a chance to test all this again until later this weekend. Plus I'll need a trip to Fry's for the resistor since Radio Shack doesn't have a 5watt in the 200 ohm size.
osphoto said:I have a NTC Thermistor rating of about : .75 - 1.1k Ohms @ 25C
This thermistor is used in a motorcycle gas tank.
Typically, a 12v lamp is used to indicate the fuel is low, Thermistor is at it's lest resistance.
I want to replace the 12v lamp with and LED. Seems simple enough since my knowledge of using an LED is using the resistor that comes with the LED in line with a power source.
This doesn't work since the thermistor has constant ground backed by 12v's and even at the highest resistance on the thermistor, the LED stays on.
What is the simplest way for me to get this to work?
I just want the LED to come on when there is no gas in the tank and OFF when there is gas in the tank.
Thank you in advanced.
I'm not sure what other info is needed.