Noisy PWM signal
I did my first test run with the intensity input on the PSU still hooked up to the pot and, for the most part, things worked as expected. I then wired up the PWM signal instead and things went downhill - specifically, the Arduino would hang a few seconds after the laser kicked in.
Figuring this was some sort of noise issue, I bodged a 0.1µF (jelly-bean value) across the PWM signal to ground and all is now well. Should this be necessary, or do I just have a noisy K40?
[pic added because everyone likes pics!]
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Hi Chris, i used to use a filter made out of a 1kOhm resistor in serie and 0.1uf cap in parallel with the pwm output. However it deemde to be unnecessary for my k40 so left it out. Non of my 5 beta user had any issues so it can be just a case of an unhappy power supply. Anyway you managed to come up with a solution which is really great. Will monitor the number of these and will incorporate the filter back into the design. Cheers, paul
I know this is a bit older topic, but I seem to be seeing the same/similar behavior.
If it use the panel to control the laser, everything is fine. If I use the PWM but turn the laser power off (mine has a separate laser switch), everything tracks fine. If I use the PWM and have the laser switch one (so the laser actually fires, I get a couple of seconds of laser before everything locks and stops.
I know enough to get me in trouble with much of this, and can follow technical directions well. What is the recommended "fix" for this?
thanks
Nick
Two months on and my 0.1µF capacitor across the PWM signal and ground is working a charm.
As Paul mentioned a 1KΩ resistor in series between the cap and the Gerbil may also be needed for a proper RC filter, but I've not needed to do that.
Thanks for the response. Good to hear your solution is still playing nicely, I'll give it a go.
Nick
Another root cause is a noisy jpeg. The background info causes spikes in the output since it is seen as real information. So filter the jpeg first and then use it in inkscape.