[eriksalo]

Hi; I've been retrofitting a Fanuc 6MB based VMC with modern electronics. I used the Pico PPMC board set (Jon from Pico has been unbelievable with support) and LinuxCNC. It's going great.

My question is about feeding the existing Fanuc spindle controller (A06B-6044-H007) with the 0-10V control voltage. My Pico DAC "stalls out" at ~2.0V of supply. If I unhook the DAC from the spindle controller, it outputs 0-10V just fine but can't get above 2.0V when connected. If I feed the controller with an external linear power supply, everything works great. Speed goes up and down correctly with 0-10V.

My assumption is that the Spindle controller needs more than the ~20mA the DAC will supply.

I'll measure the actual current used in each case.

Has anyone encountered a similar problem?

Thanks

[eriksalo]

I measured the current when operating the spindle amp from an external power supply, the circuit takes 28mA, so that seems the issue. Has anyone else run into this?

[cjfisher]

Erik,

Have you considered using a Rail to Rail OpAmp hooked up as a voltage follower? Something like a Texas Instruments TLC2272CP (digikey part# 296-1812-5-ND) might work... as it doesn't need a +/- voltage input (aka you can run it on a 0 to 16 volt supply) and it will kick out 50 mA per channel. You could even parallel the two sides and double current output.

Cj

[guhl]

Inspite of supply 3-32V may be used, for your case not less than 11V needs to be used.