Assuming the 20V power supply is DC, sure, just calculate the resistor value to limit your LED current. If the 1.5V you speak of is the voltage drop across the LED, a 1kΩ will limit the current to 20 mA; the resistor will need to be 1/2 watt or larger.Hi,
Could someone tell me is it possible to run 1.5v led from a 20v power supply if current consumption was restricted, or kept under the max allowable current for the led?
Regards NM
A 5kΩ resistor will only need to be 1/8 watt or larger.The answer is yes. You will need a 1K-ohm resistor in series to limit the current to 20mA. A 2K-ohm resistor would bring the current down to 10mA. You may start out with 5K-ohm and see if 4mA will give you sufficient brightness.
In other words at the time the coil was not capable of suppling power to any type of load no matter what size? An led would have appeared to be a very light load.the ignition coil is a high-impedance source
Without seeing the voltage waveform on the oscilloscope, one has to guess a lot of possibilities. We can start to check what the meter really measures since the signal is not DC or sinusoidal. Then we need to estimate at which voltage and for how long the LED conducts in the reverse direction since it is an AC pulse coming from a transformer (not digital, between Vcc and ground for example).Yes 20V (+/-2V) was measured across the led terminals.
The dangerous thing in an electric system is power not voltage,for example a 1000v with 20 micro Amperes (power is 1000 * 0.00002 = 0.02 watts) would not give me a shock ,but a 100 volt with 50 Amperes (power is 100 * 50 = 5000 watts) would give me a shock.Anyway electric system may be unsafe, so just don't assume by the level of voltage only.Doesnt this show that the kV supply would be harmless
by Jake Hertz
by Jake Hertz