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Pulse Repition Frequency.

PostPosted: Thu May 13, 2010 7:44 am
by Tweakie
Hi Guys, I wonder if you could help me out here.

I am using the typical Chinese PSU with 0-5 Volt potentiometer control of the maximum tube current setting.
I can vary the duty cycle of the TTL trigger from say 1% to 99% and my question is what would you consider to be the optimum PRF for this signal please ?.

Tweakie.

Re: Pulse Repition Frequency.

PostPosted: Thu May 13, 2010 11:26 am
by bdring
20 khz is what I generally see. It is usually somewhere in the manual.

Re: Pulse Repition Frequency.

PostPosted: Thu May 13, 2010 12:29 pm
by Tweakie
Hi Bart,

Thanks for the fast response. Sorry but I don’t think I phrased my question very well.
I am using an analogue signal (0 to 5V) for the tube current control so no PWM required here.
It is the TTL input which is usually either 0V or 5V (<0.3V to >3V) that I wish to alter the duty cycle of. As the standard PSU switching response time is ≤ 1mS I am assuming that anything over 1kHz will be worthless and was just wondering if there was an optimum PRF already established.
What is the fastest speed the TTL input is switched on/off when raster engraving I wonder ?.

Thanks,

Tweakie.

Re: Pulse Repition Frequency.

PostPosted: Thu May 13, 2010 12:44 pm
by lasersafe1
The answer you are looking for is here:

viewtopic.php?f=6&t=36&start=20#p501

I made a detailed measurement of the laser drive signals during a fast raster.