5v laser and other questions February 02, 2021 03:40PM |
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Re: 5v laser and other questions February 02, 2021 04:53PM |
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Re: 5v laser and other questions February 09, 2021 05:51PM |
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Quote
VDX
.The power is defined by pulse-length - so 0-5V analogue input to my drivers "set power"-input will result in pulse-lengths from 5 to 500 Milliseconds ,,,
0/12V fan output ----- 8.2M --+--5.6M----- GND | | 0/5V to laser
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Re: 5v laser and other questions February 20, 2021 09:45PM |
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This was my very first thought on how to do this. I dont have those resistors but I am getting a bunch in the next days to weeks depending on china. I am getting some 1 million and some 680K. By my calculations that would give me a max V of 4.85. Should be good enough.Quote
frankvdh
Quote
VDX
.The power is defined by pulse-length - so 0-5V analogue input to my drivers "set power"-input will result in pulse-lengths from 5 to 500 Milliseconds ,,,
The input isn't analogue in the voltage domain. It's digital (TTL)... 0 or 5V. The analogue aspect is, as you say, in the time domain (PWM). The OP was talking about generating a 5V signal by using PWM to modulate the 12V fan output at 106/255 or less duty cycle. Which won't work because
(a) more than likely it would result in a 12V output (capable of multi-amperes) connecting for 2-200 milliseconds at a time to an input only rated for 5V. And that's only going to end badly.
(b) if you use some capacitors and resistors to smooth it out, you'll get an analogue signal, not digital. At best it would only work for a small range of duty cycles
(c) the smoothing would delay the signal, so the laser would switch on/off later than it should, when the carriage is in the wrong position.
Better would be to use a pair of resistors to divide the 12V down to a 5V output. But you would want large vales (e.g. 8.2M, 5.6M), otherwise there would be large currents when the signal was at 12V.
e.g.
0/12V fan output ----- 8.2M --+--5.6M----- GND | | 0/5V to laser
But best would be to use a 0/5V signal in the first place.
Disclaimer: I am not an electrical or electronic engineer.