Mode Zero

Hi All,

I've been thinking recently (after a couple of deadsticks) that an onboard glow driver would be a good option. However the commercial ones seem pretty expensive, so I though, somebody on this forum must have already come up with something, or could in ten minutes. I guess all I'm really looking for is a high current low voltage switch that I can control from a receiver channel. (Or control from the throttle channel with a bit of cunning Tx programming.) As Einstein once said, 'everything should be as simple as possible, but no simpler.'

Thanks.

I used to build discrete component boards way back when.
The switching part I used then was expensive, I think an opto mosfet of around 5A or so.

About 2 years ago started on making an ATtiny85(module type) controller and run-of-the-mill mosfets which works really well.
This was on the four cylinder boat engine but same same or very similar for single cylinder aircraft or whatever.
Not my design by any means.
See if I can find it amongst all the files and mayhem here.

Below is the original designer's write up to start with.
Note that programming the ATTiny85 module can seem tricky to begin with but as long as one follows point to point, like falling off a log really.
https://openrcforums.com/forum/viewtopi ... #p118270

Hi Ian, Its a simple project if you want the satisfaction of DIY, but economically, as we found with escapement switchers, cheaper to buy, eg:
https://www.pololu.com/product/2804

I can send you a PIC chip FoC that switches its output at 1.6ms but you would need to add the mosfet or relay stage
PM your postal address if you fancy that idea.
Cheers
Phil

Might be interesting to make a very fast switching MOSfet, that could do PWM current control - then you'd be able to use a higher voltage, such as that from a single lithium cell to power the glowplug - there would be no need for nickle cells, or additional voltage regulators. The control signal would set the power level, so you'd be able to control how hot you want the glowplug from the transmitter: that might be useful to allow a high-heat starting glow, and a lower heat for maintaining a reliable tickover, while prolonging the glow battery's endurance.

I suppose what I'm describing is just a brushed motor ESC. I wonder if anyone has ever pressed one of those into use as a glowplug controller? They do normally work at even higher voltages than I'm suggesting though - usually 6V or more.

What starts out at US$12.50 quickly gets to almost AUD $19.00 plus postage and handling which invariably doubles the price.

Parts I used were an ATTiny85 module off Ebay or similar around AUD$6.00
A couple of 1/4w resistors, an IRLB3034 mosfet AUD$10 for 10 pieces and a 10k multiturn pot.

Depending on voltage sources, may require a boost converter also ($3)

Obviously other bits and pieces which will push up the cost such as a $2 programmer but still way short of AUD$40.
Depends I guess on what the Op has in the bits and pieces box.
Avoids the use of a relay which would be subject to vibration.

I was just thinking that a relay would make it simpler Jeff


Previous discussion here Ian: viewtopic.php?p=177#p177

Mine is item P11 on the Archive page of singlechannel.co.uk right-click, save-as

I'm with Phil. I've used old relay switches (opto) intended for brushed motors (when esc cost a fortune).
Simple, reliable and there must be hundreds laying about in modellers drawers.
Shaun.

Wouldn't it be simpler to fix the fault causing the dead sticks?

It depends on the motor. I had a MK1 OS Gemini 120 twin that always lost one cylinder on low tick over when airborne ( perfect on the ground though). Tried numerous fuel types/ blends, props and plugs , it never solved it so I used a glow driver that automatically switched in below a certain throttle setting. Had the additional benefit that I could just flick and go and didn't need 2 an external glo drivers.

Thanks very much for everybody who has posted ideas. Very much appreciated.

I'm sorting through them to try to figure what to try first. I like the brushed esc idea, I have a couple of them, but I don't use brushed motors any more, so it would be interesting to hook one up to a plug and see what happens... Otherwise jhsa's idea seems pretty good. I have a bunch of microcontrollers of various types so I may be able to adapt one of them to the task, but my knowledge of electronics could be engraved on the head of a pin so I might need a bit of help there... I also have a switch I can plug into a receiver, but it's for switching leds on and off, so not sure if it could handle the current. It might be able to drive a relay though, or the electronic equivalent, and that might do it.

Lots of great ideas. Thanks again.

Ian