Micro Controller Pulse Circuit

[CLaNZeR]

Spent this week drawing up a Circuit that hopefully will help people wanting to build their own pulse motor but may find the electronics a struggle.

I will release the PCB, Firmware for the Micro Processor and Windows Config software when fully tested, all for Free, all I ask is for feedback.

Find below PCB V3 draft, that I will etch this weekend.

It uses a Microchip Pic 16F876A to control the timing of switching upto 4 Mosfets (Connected to Electromagnets or anything else you want to pulse!)  and also 4 Opto Switches to detect the position of the rotor. I have attached the datasheets below, but you should be able to swap out the Mosfets for any you want to use as long as the Pin config suits.

The power for each Opto Switch is controlled via some PNP transistors, so you can choose to switch them off and hence pull less current if only using 1 Opto switch and 1 Coil output.

The Pic Processor is connected to a RS232 level converter chip that allows it to connect to the serial port of a computer and this will allow two things to be achieved.

1.) Download and program new Firmware into the Processor as new versions get released.

2.) Configure the timing and functions of how you would like the processor to act via a simple Windows program that downloads the config you want.

An example is , if you wanted to switch one Electromagnet on everytime the first Opto Switch detects the position of the rotor and to pulse it the Electromagnet for one second, you would simply tell the windows software this is what you wanted and then it would download the config to the processor. If you wanted to add say a 10us delay after detection, again this can be downloaded, which will allow fine tuning of the pulse firing.

Another example you wanted to use 3 Opto Switches with one Electromagnet, this time the distance is measured from Opto Switch number one and Opto Switch two to get the speed that the rotor is running at  and this then determines the timing pause needed beofre the next pulse is applied on the Electromagnet.

Of course you could build a pulse motor with four coils and four Opto Switches, it will be upto you.

I will draw up the schematic this weekend and any feedback on what else could be added or any tweaks would be appreciatted.





Above Draft 3 of the PCB. ****UPDATED 25/3/2007****

I have tried to make the tracks as thick as I can for people making their homemade PCB's and increased Pad sizes where possible.

Regards

Sean.

[barbosi]

I think this is a great idea and thanks for making available your efforts for free.

Before even being released, I dare with a comment. Not sure if there are ports available, but I think it would be great to have also a tool in this design (while adjusting pulses, to be able to display RPMs). Just a thought though, don't take it hard on me. I being thinking beside scopes and other fancy tools, it would be interesting to know what the controller think the speed is. That's all.

Cheers.

Maybe redundat serial transmision back to PC... Then it's PC's program to handle data and display it. This way wouldn't modify PCB.

[CLaNZeR]

Hi Barbosi and thanks for the feedback.

I was thinking this also but if the Micro is busy doing the coil pulses and some calculations I was a little concerned about the accuracy of the Revs being sent back to the PC.

But now I have an idea that I will couple up one of the Opto Switches onto a spare buffer on the RS232 converter chip and get that to toggle Pin 7 on the serial port (RTS) line. This way the Software running on the PC can simply do the calculations and display the Rev Counter without it interfering with the pulse timing.

Will go see if I can squeese it in!!!

Regards

Sean.

I think this is a great idea and thanks for making available your efforts for free.

Before even being released, I dare with a comment. Not sure if there are ports available, but I think it would be great to have also a tool in this design (while adjusting pulses, to be able to display RPMs). Just a thought though, don't take it hard on me. I being thinking beside scopes and other fancy tools, it would be interesting to know what the controller think the speed is. That's all.

Cheers.

Maybe redundat serial transmision back to PC... Then it's PC's program to handle data and display it. This way wouldn't modify PCB.

[CLaNZeR]

I have spent today drawing up the Circuit instead of running off and making the PCB as I want to make sure I have got it right, so any more feedback would be cool, especially if something does not look right.

I have now added also a 20K Pot that can be used to alter the timing while the Micro Processor is pulsing away and also the 4th Opto Sensor now feedback to the computer serial port direct, so it can be used as a Rev counter without interfering with the Micro Processor timing routines.




Regards

Sean.

[barbosi]

Very creative idea about pulse counting in PC!

Now brief comments:

- I don't see any protection for CMOS agaist BEMF pulse. Of course protection can be mounted out of PCB in parallel with coil, but is a shame to waste BEMF. This is the gold mine to harvest free energy. Maybe a neon lamp in parallel with CMOS will give you a chance to harvest at least partially this pulse...? See also: http://www.overunity.com/index.php/topic,1988.msg25252.html#msg25252

- Related also to RPM calculation; if processing time is a concern, then it will be also for all opto signals to be processd when they arrive at the same time. You'll have multiple processes competing for calculation time in real mode. This in case you use a RTOS. Just a thought...

Anyway no body thought it will be a smooth ride, and I presume this is why you asked for feedback. A good start is a half way towards a finished job.

Regards.