Opto Isolated On Board Glow Driver/Switch

[pbunn]

I put this little Glow Driver/Switch together as a project for my son's Extra 300 that had a tight cowl and needed a lightweight on board glow driver.

I used a small PIC12C508 ($1) and a 6 pin dip opto relay module ($4.50). I used Bruce Abbot's software that he presented here a few days ago. That made getting it together much faster. Bruce's software has a large amount of deadband and is latching. Thanks again, Bruce.

This is the final PC Board layout, postage stamp sized. It is fully opto-isolated from the radio system power supply and can supply 4.5 amps at voltages up to 20 volts max. The on resistance of the module is so low that power disapation in the switch is effectively nil. At 20 volts, It can switch up to a 90 watt load - that is totally isolated from the RC electronics.

Total cost is less than $10 including the servo connector. If there is any interest, I will put the PC board layout and construction details on the net.

[flatfour]

What do you use to switch the load?

Forget it....... I was first thinking the opto isolator was between the PIC and the RX

[VinceHaworth]

That looks really neat and compact. Please share your schematic and hex code. :)

[Gary Warner]

I've been looking at the datasheet for the PVN012. Cool IC. Thinking... :)

Gary
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[Chippie]

Brent Dane did an opto glo switch based on the same opto....http://www.cliftech.com/pdf/OptogloII.pdf


No need to go using a pic ( and having the probs programming a 12C508 into the bargain...that a lot of people have :p )

[Gary Warner]

I put this little Glow Driver/Switch together as a project for my son's Extra 300 that had a tight cowl and needed a lightweight on board glow driver.

I used a small PIC12C508 ($1) and a 6 pin dip opto relay module ($4.50)...

After looking at the link to the non-pic driver, I noticed a damper diode across the glo-plug. Are you using one? I didn't see one on your board.

Gary
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[pbunn]

No - no diode - maybe a mistake - but the glow plug is not that inductive (maybe it is - but I doubt it) - and with the distributed resistance of the wire - I would think the Q would be low. The opto is rated at 20 volts and the cell is 1.25 volts - It looked like overkill - I have had no problem - with a motor or solenoid - I'd add it .

Pat
Bunn

[Gary Warner]

I'll agree, for now, subject to change if you report problems. I noticed that the on/off switching speeds are on the order of 5 ms. Fast enough, mind you, but unlikely so fast that the magnetic field of such a small coil would collapse with enough EMF energy to exceed to reverse limits of the IC. Just thought I'd mention the diode incase they know something you didn't think of.

Gary
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[pbunn]

Yes - he talks about using it as a switch for other things and in his first article - he talks about switching a speed 400 motor - that would definately require a diode.

The IR chip is really a nice device for use with a PIC.

[pbunn]

Here is a gerber file of the board.

I use an ancient PCB system - that designates the solder side as a .sol file

The forum want allow a .sol upload so I have changed the file name to TXT - You must rename it to a gerber type file

If you need a printer program to print it, I can supply a DOS based printer.