Hi all, I'm breaking down three LED solar lights for their components with the intention of hooking them up to my Arduino and playing with them. My ultimate goal is to add an old phone lithium battery in order to get a solar charging circuit to light some LEDs at night. I'm pretty fresh to electronics and so right now I'm just trying to establish the values of these resistors and hook them and the LEDs up to a battery to make glorious light!
My problem is that the resistance I measure across either of the two large resistors with my multimeter is much lower than the value I work out from their colour code. The three smaller ones all produce correct values of 7.5, 10 & 100 Kohms. Are the resistors likely to be duff or is it possible that some aspect of the circuit is screwing with my measurements?
You generally cannot make reliable resistor measurements on resistors that are in a circuit. I would rely on the color code as it's hard to mess that up (or desolder the resistors and measure them when unconnected to anything).
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The Basic Motor Driver: simple, inexpensive motor driver for 1 stepper motor or 2 DC motors
My problem is that the resistance I measure across either of the two large resistors with my multimeter is much lower than the value I work out from their colour code.
You typically can't measure a resistor resistance while it is wire into a circuit, as other components will effect the reading. You need to lift at least one lead off the circuit board to take a valid ohm reading of a resistor.
The previous posts are on the money regarding in-circuit measurements. But how do you interpret the color codes?
The large resistor on the right looks like yellow-purple-black-silver, which would be 47? ±10%. Not as sure about the colors on the other one, if they are brown-black-brown-silver, that'd be 100? ±10%
I agree with WESTFW. The CYAN device color code markings bear a strong resemblance to inductor markings. This is also likely, since this circuit probably is a DC-DC converter for LED.
Hello peeps, thanks for more replies & input. I'm afraid I can't read the PCB markings underneath them, westfw. I didn't realise they might not be resistors.
Pwillard, do you mean that its a buck converter? I googled "DC-DC converter" and "inductor" to find that- I have no idea what one is but I will read up on it now.
RoyK, I'm just embarking on my journey into electronics and I quite enjoy breaking things apart and scavenging. I've also been unemployed for nearly a year and so even a few dollar is a lot at the moment.
Guys... Here two small program - ( Work in Windows XP ) Color code program. Both are EXE file. Just download and run it. File size is about 60 Kbytes ( each file ). Have fun
