Hi guys,(adsbygoogle = window.adsbygoogle || []).push({});

Right a really simple question here and I'm missing something really basic.

I have a simple LDR circuit that I can't seem to get working. I'm completely adept at Electronics and it's use is just for a small project I'm working on in my spare time.

Attached below is a picture of the circuit I have now. I have previously had this working with 200mA and 12V. The bulbs are both 6V and the transistor is a TIP120. I previously used a 2.2k Ohm fixed resistor followed by a 10K Ohm (Max) variable resistor set at around 5K Ohm. The LDR goes from 3K Ohm uncovered to 65K Ohm covered.

Since I had this working with a power pack on 200mA, I then changed this to a set of 8 x AA batteries which gave me 12V at 4A, and this is where I got most of my problems. I've used Ohm's law numerous times getting various figures, however I really don't think I'm doing it correctly.

I've been trying to figure out the current going through the circuit using Ohm's however, reading up online, I know I get the current across resistors, does this mean what is coming out after the resistor or does this mean I take this from the battery current?

Again, I apologies for the real simple question but if anyone could help me calculate the resistance I need to enable my circuit to work and how it is done I would really be in your debt!

Many thanks!

Brad

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# Simple LDR Circuit problem...

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