- Joined Nov 7, 2021
Actually no. I want to make a 5 watt led lamp like this.Hi
On top of above
they are correct
are you sure the led requires 1amp??
The circuit in #1 is a capacitor supply. The cap does the divide down with out heat loss.That would require at least a 300Watt dropper resistor.!!!
The circuit in post #1 is much like a constant current source not a voltage source. Getting 1A from it is very hard and require a very large capacitor. If you series all 10 LEDs then you need 33V at 150mA. (which that type of supply will do) You should run the LEDs a little less than the absolute max current.(10 pieces of led) or parallel
There was a time then radios (some) lived on the power line with out isolation. The metal chasse was directly connected to one of the power wires. (never know which one, 50:50 chance)We used to make our own Radio receivers
so.. the output voltage in this circuit always changes depending on the led used?
how do you get these values? especially for R1 and R2Note I would use a capacitor rated for power line use. R2 will run about 1.5 watt of heat. Probably should take that down to 16 ohms to get to 1/2 watt. I used 50V diodes just to show that you do not need 1N4007 high voltage diodes because the diodes do not see power line voltages. 1N4002 = 100V would be safer. LOL
Adding a 100uF 50V cap across the LEDs will reduce the ripple.
R1 across the capacitor is there to discharge the cap when power is missing. Its value is not important. 1M to 10M. It needs to handle 250V across the part to do not use a very small part. (no 1/4 watt)how do you get these values? especially for R1 and R2
this is for my school project. which is where we have to make an unsafe transformerless led driverIt would be safest to use a transformer to reduce the (potentially lethal) voltages down to a safer level (though you still need to build it with safety in mind), then the LED control is easier - why can't you use a transformer?
OKthis is for my school project. which is where we have to make an unsafe transformerless led driver
You are not there and we don't really know ...............Then someone at your school should know better than to endanger its students
You need a much larger value for C1 - it needs to be about 15uF (and R2, R3 and R4 need to be much smaller).
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by Jeff Child