My Charge-Pump circuit

[Guillote]

Well I am starting the build of my control box. I have been simulating this circuit and it looks good. Here's the pic

Update 07-26-2007

The pump below is based on the Mariss’s circuit at http://www.artofcnc.ca/ChargePumpSafety.pdf. The circuit turns off in 1 millisecond, but it is turn on delayed 4 milliseconds in order to avoid a false triggering. It has spindle on/off control and three limit switches pairs that shuts down de geckos supply when are activated.



Comments always welcome,
Guillermo

[Mongkol]

Hello Guillermo,

I am wondering with charge-pump. What is the function of it? I ever found
in DB-25 pin of parallel port,for Mach3. I am not good at electronic system.
Please advise if you know.

Cheers,
Mongkol

[David_Web]

The computer sends a lot of rubbish etc to the lpt ports and that could do anything from moving some axis to wreck havoc.

With a charge-pump you need to feed it a stable 12KHz for it to activate motors etc. The computer will not send out a similar signal by itself but need a program to do it.
Extra safety if you will so that you don't have to manually turn on and off things to prevent damage.

[Guillote]

Hi, Mongkol

Any machine tool is potentially dangerous. The charge-pump is a safety device. Mach3 will output on the parallel port a constant pulse train whose frequency is 12.5Khz whenever it is running correcty. You can use this signal to enable your axis and spindle drive. This function is often implemented in commercial breakout boards. Soon I will update the circuit to include spindle control.

Guillermo

[samakthachai]

Hi Guillermo,
It's possible or not if you will share the full option wiring diagram of cnc router.


Thanks
Samak

[Guillote]

Hello Friends,

The idea of using the internal supply of the PC to power de relays is tempting me . The problem I found is that when I measured the voltage difference of the parallel port's GND to the power supply's GND it was 0.25Volts . I can't connect them together since this might produce smoke or burn a track so I am thinking to use power supply's GND and leave parallel port's GND unconnected or at most connect the LPT_GND with Power_GND through a resistance. I would like knowing what do you think on the matter?


Comments always welcome,
Salu2, Guillermo

[ajaydevb]

Can anyone suggest a dedicated ic for charge pump function for use in mach3 bob?

[Al_The_Man]

Google for missing pulse detectors, or watchdog timer circuits, there are many IC's that can be used starting with the simple 555.
Al.