Electrical schematics drawing software

[SparkyLabs]

Kicad is good but I had to give up for professional work but the schematic side is OK once you work out the library nightmare. Diptrace has a free version but I'd not recommend wasting money on it.

Sent from my phone so mind the autocorrect.

[Jonathan]

Kicad is good but I had to give up for professional work but the schematic side is OK once you work out the library nightmare. Diptrace has a free version but I'd not recommend wasting money on it...

It's not what the OP needs, but for designing PCBs I think KiCAD is worth persevering with. I have Altium on my work computer, but for me, the slight functionality it gains over KiCAD is negated by the software needing a licence to run. I also found Eagle and Diptrace easy enough to use, but again they cost money for anything serious.

I use it also to generate PCB layout. Here is the latest thing I made with it:

https://adapting-camera.blogspot.se/...stretcher.html

Instead of making this PCB, you surely could have used a smaller series resistor for the LED a lower value, as the issue is just the low duty cycle? LEDs are fine with pulses of higher current, so long as the output is never stuck on...

[Doddy]

Instead of making this PCB, you surely could have used a smaller series resistor for the LED a lower value, as the issue is just the low duty cycle? LEDs are fine with pulses of higher current, so long as the output is never stuck on...

I normally read everything you write, Jonathan, with considerable interest and intent to learn; however, the above is not sound advice : Most designs would work on a I_F=10-20mA with an I_F(max) of 30mA or so - and so limited ability to increase the current (and therefore the emitted optical energy) within the constraints of the device; some (though by no means all) manufacture's datasheets will provide a peak I_F rating given explicit constraints (e.g. 100mA at <10% duty-cycle with a pulse-width < 1ms), unless the OP is designing within the limits of the LED datasheet then exceeding the maximum rating of the device will, in all probability, reduce the reliability of the device and result in premature failure. You're also suggesting something that would cause significant current spikes on the driving system, which at reasonably high frequencies could cause EMC issues and possibly problems with the drive system. It's a design, designed to fail.

What the OP did with the pulse-stretcher is a well-engineered solution to his problem (though I'd do it differently!)

[Jonathan]

Fair enough, I didn't think this one through - the signal should at least first be buffered (as the OP did) as we don't know the drive capabilities of the BOB and wouldn't want to adversely affect the signals to the driver optocouplers. Even so, as you say, there is a chance of the high di/dt causing issues elsewhere.

If obtaining the required brightness with any method requires operating above the LED pulse current rating constraints, then my proposal is moot. Although I would question how much the reliability matters here - after all the LEDs are just a neat accessory to the machine.