.:madworm:.'s photos with the keyword: simulation

I need a step-up LED driver for the 12V LED bar I got at seeedstudio. I'm planning to put 2 of these on my bike and power them with 4 AAA cells. The LT1618 supports constant current drive and a max. Vout setting. It can be used as a variable voltage step-up power supply with over current limiting too.

Mathematica was used to create this.

not perfect at all

A single supply non-inverting amp with pulse stretcher. It's also got an offset 'knob'. The LM2940 is a dual amp, so maybe I'll add some more pulse shaping. It sucks that all the easy stuff requires symmetric supply voltages. But using just 5V also means that there won't be any over-voltage or negative voltages that could kill the AVR. The blue curve will be integrated by a microcontroller.

A single supply non-inverting amp with pulse stretcher. It's also got an offset 'knob'. The LM2940 is a dual amp, so maybe I'll add some more pulse shaping. It sucks that all the easy stuff requires symmetric supply voltages. But using just 5V also means that there won't be any over-voltage or negative voltages that could kill the AVR. The blue curve will be integrated by a microcontroller.

A single supply non-inverting amp with pulse stretcher. It's also got an offset 'knob'. The LM2940 is a dual amp, so maybe I'll add some more pulse shaping. It sucks that all the easy stuff requires symmetric supply voltages. But using just 5V also means that there won't be any over-voltage or negative voltages that could kill the AVR. The blue curve will be integrated by a microcontroller.

As the 8pin LM2940 op-amp is a dual amp, I've distributed the amplification to both amps. The first stage still adds an offset and has adjustable amplification, the 2nd stage is a fixed at a factor of 11. I've also added a low-pass filter at the output to smooth the signal some more. C5 was added for AC coupling and must be at least as big as C1. D2 was added to allow C5 to be discharged and be ready for the next pulse.