Flasher circuit using a BD679

[Wobbin]

If you're sure that you pave the pins connected correctly (see attached) then the next suggestion, assuming you have a multimeter, is to measure the voltage between the base and emitter of the BD679 to check what the BOB is sending.

Cheers
Robin

[ozspeedway]

Hi Robin

Just ducked down and checked the pinout and all as per required. Measured the voltage as suggested and got 0.04v yet the LED is glowing and not flashing. Just for kicks I measured between the base and the collector and got 12.67v. The brain was active and "flashing" yet it made no difference to the LED. If I disconnect the parallel cable the LED goes out even with power still applied to the BOB. I have tested this with 2 different BOB's, a PMDX 122 and an MB06-v2 from homann designs in Aus, both show the same behaviour. The LED stays lit even when pin 14 (assigned to OUTPUT1) is disabled. Got me stumped at this point.

Cheers

[EddyCurrent]

Bruce,

This is the drawing for mine, just checked it at the machine itself.

[ozspeedway]

Thanks Eddy, looks just like what my version is. I now suspect our differences come from you using an ethernet smoothstepper and me using a parallel port. I have a strong suspicion that the PC is filtering some voltage via the P/port that the BD679 is seeing. I can confirm that by taking the p/port cable off the BOB and the LED goes out. Of course I can't then test Pin 14 out. However, an ESS is in my immediate future (next week some time) so I will see if my gut feeling is correct.

Cheers
Bruce

[EddyCurrent]

I've just had a look at the PMDX manual, it looks like you should be using pin 14 or 16 of J8 and JP3 should be set to 'outputs enabled', that's what it looks like after a quick read anyway. The outputs have an LED so it should be easy to see the state of your chosen output. I can't see the ESS making any difference so I would disconnect the flasher and concentrate on getting your bob output to go on and off from the software and not using the Brain function. When you get the output to operate correctly then connect the flasher and it should go on and off with the output. Now bring the Brain into operation and provided the logic is okay the flasher should operate.
It may be that the lamp is dim because it's being switched at high speed, try a multimeter with frequency range across the lamp.

[Wobbin]

What's the 'brain' function then ? Forgive what may be a dumb question, as I said I'm new to CNC...

[EddyCurrent]

What's the 'brain' function then ? Forgive what may be a dumb question, as I said I'm new to CNC...

This is the info that Bruce is using for his machine, see the Zip file attachment for the Brains.
http://www.mycncuk.com/threads/6565-...2213#post52213

Brains are a feature of Mach3 software, you can get an overview here;