Dusk - Dawn Switch (LDR)

I came into this thinking that all the components have pins and those pins connect to each other to make something work. When it comes to the transistor i did not understand why it was needed i just accepted that it was. What I know about the transistor is very little. I do know that in this circuit it will keep the pot from burning up but i dont know how it does that. If i were to guess id say its not the voltage that destroys components but the current.
From what I have read the base voltage is 0.6v current begins to flow. This is referred to as gain.
I suppose if i did not need a pot i would not need a transistor.

If you could help me select the correct resistor for R1 and any other modifications to make this work id appreciate it. These leds are going into a double faced clock. there will be one led placed at each hour segment. I will use the pot to adjust the light so its just bright enough to illuminate the clocks face.

ThomsCircuit said:

I came into this thinking that all the components have pins and those pins connect to each other to make something work. When it comes to the transistor i did not understand why it was needed i just accepted that it was.

Click to expand...

It provides MANY advantages, not the least of which is avoiding a far more expensive pot.

ThomsCircuit said:

What I know about the transistor is very little. I do know that in this circuit it will keep the pot from burning up but i dont know how it does that. If i were to guess id say its not the voltage that destroys components but the current.
From what I have read the base voltage is 0.6v current begins to flow. This is referred to as gain.

Click to expand...

No, as it's a darlington it requires double the normal voltage.

ThomsCircuit said:

I suppose if i did not need a pot i would not need a transistor.

If you could help me select the correct resistor for R1 and any other modifications to make this work id appreciate it. These leds are going into a double faced clock. there will be one led placed at each hour segment. I will use the pot to adjust the light so its just bright enough to illuminate the clocks face.

Click to expand...

R1 isn't at all critical, or even strictly required, but 1K should be perfectly fine.

Nigel Goodwin said:

No, as it's a darlington it requires double the normal voltage.

Click to expand...

I chose the darlington because of the number of leds. On a previous project there were just 8 leds. Signal from a counter IC. And a TIP was suggested.

I'm glad I got this right. Even by accident. I'm pleased with my progress. I can understand basic schematics and adapt them to my own.