PWM to Voltage Converter Issues - Again!

Nightowl

Tested the converter and it is defective. I cannot get more than 8.4V out from the spindle control pins when I actually need 10V, so a new one is on order!

Thanks for pointing me in the right direction in getting this sorted.

Nightowl

@gloomyandy

I've ordered two of these, from different manufacturers (at least as far as the trading name goes) but both of the new ones have an output of between 0 and 8.6VDC, and turning the small screw has absolutely no effect at all.

The input voltage is 12VDC (measured) and the PWM voltage is 5VDC (measured) to get an output of 8.4VDC, or a PWM voltage of 0VDC to get an output of 0.0VDC

So now I'm clean out of ideas.

dc42

@Nightowl can you trace the schematic of them?

Nightowl

@dc42
Not very well, I'm afraid. What would I need to know?

I could provide a photo

dc42

@Nightowl I have one somewhere, but it may take me a while to find it.

Nightowl

@dc42 Isn't it in the cupboard, behind the clock?

That's where I keep finding 'lost' stuff

T3P3Tony

@Nightowl said in PWM to Voltage Converter Issues - Again!:

've ordered two of these, from different manufacturers (at least as far as the trading name goes) but both of the new ones have an output of between 0 and 8.6VDC, and turning the small screw has absolutely no effect at all.

I would return them as faulty as a start!

Nightowl

@T3P3Tony

Yup, they're gone!

Further to this, though... The one that does come close still only provides 9.6VDC, and that's with the brass screw all the way in, but I had to use 24V directly from the PSU, not 12V/GND supply adjacent to the VFD/Laser/Servo Driver header.

I really don't understand why the converter won't give the 10V the spindle needs.

Perhaps it's time to persuade Duet to design it into the control board

Nightowl

So, I've been out to the workshed (too small to be a workshop, too big to be a toolshed) and, with the (cheapest) PWM-Voltage converter managed to achieve the following:

Programmed - Actual Speeds
M10000 gives 10,150rpm
M14000 gives 14,010rpm
M18000 gives 18,000rpm

As this is the speed range within which I primarily use the spindle, I think that'll do!

Thanks to you all for your help!

alankilian

@Nightowl EXCELLENT!!!