Here’s an interesting circuit. By using NPN for high side in emitter follower I’m able to add current to circuit as led are added. Due to the parallel resistance of the led the voltage sags as more are added. So limited to 1-3 LED would give acceptable results.
What I want to do is have the current go up linearly and have the circuit at 18 mA each time an led is switched on. Currently it starts at 18mA and drops to 15mA by the 3rd led. Which isn’t bad. But can we get perfect?
What is happening is that it starts to sag a little. Can anyone see how to keep the current consistent on each led as it’s being added?
What I want to do is have the current go up linearly and have the circuit at 18 mA each time an led is switched on. Currently it starts at 18mA and drops to 15mA by the 3rd led. Which isn’t bad. But can we get perfect?
What is happening is that it starts to sag a little. Can anyone see how to keep the current consistent on each led as it’s being added?
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