ruriimasu
Enlightened
- Joined
- Oct 17, 2007
- Messages
- 573
As per the title, how do I tell them apart? Kindly guide me, thanks
I think it should be possible to make an LED tester yourself from 3 AA cells (approximately 4.5 V) and a 1000 ohm (1k) resistor. Connect the resistor in series with the 4.5 V battery to limit the current to about 5 mA or so in the event of a short or a failed LED.
Touch the circuit momentarily to the LED connections. Most LEDs will light up if connected the right way round and will fail to light if connected the wrong way round. Mark the positive lead with a red marker pen or a dab of TippEx correction fluid or something.
Once you have the polarity identified, you can feed more current through the LED in the forward direction to make sure it lights up properly. Most miniature LEDs are limited to about 20 mA in normal operation.
You can use any battery with a voltage between 4 and 5 volts. A 1000 ohm resistor is brown-black-red. The value is not critical, something between 500 ohms and 1000 ohms should be fine.Wow. I got more than I asked for and now I can make my own LED tester can i just use one 4.2V li-ion 18650 instead of 3 x AAs? what color is an 1000ohm resistor, i was thinking i maybe able to pull one out of an unused device thanks for your info Mr Happy