New guy here, need some glow plug circuit help

[BoxxerSix]

My name is Adam Hennessy and I own a small auto/motorcycle fabrication shop in upstate NY. I'm currently wrapping up a ~13 month long, $200K project in building a one-off custom chopper for a customer. You can view many pictures of this bike at the link I provided below. Click on the thumbnails for larger puictures:

www.ss-graphics.com/_ERodTech%20Rides/


My problem revolves around the exhaust and nitrous/propane purge system. The exhaust system you see in those pictures flows under the seat, through a set of midpipes, and out through the pylons into side canisters which double up as dummy jet engines(Jet's football team based bike). There is also a nitrous system on this bike and the purge of this system is dumped into the midpipes, combined with a bit of propane, to emit blue tint flames from the back of the canisters(again, the dummy jet engine look).

To aid in the ignition of this gaseous mix I've install two OS A3 style glow plugs into the midpipes under the seat(one per pipe), slightly downstream and directly across from the input nozzles of the nitrous mix. I had to go with this type of setup due to the very small space I had to work with. The typical "sparker" style flamer exhuast systems were too bulky to fit anywhere on this bike in a clean sense.

Right now I'm having trouble getting the plugs to glow at all. As far as my electronics skills go, I guess I'm ok or average. I tried using simple power resistors to cut down the 12-14v battery input voltage to about 2 volts, but i'm getting only 100-200 mA across the circuit. Not enough to get heat. I searched this site and most say I need 2-3A to get these going good and hot. So now I'm stuck. I need to produce some kind of driver circuit to operate these glow plugs(2) using a 12-14 input voltage, but be as compact as possible.

The only other option I thought of was to build a simple driver circuit using a small cell pack like a four AA size reciever size and run that off a relayed circuit. IE, press button to operate relay, which in turn closes the cellpack circuit to drive the plugs. My only problem with this is NOT being able to EASILY get back to the pack to recharge the cells, nor any visually appealing way to mount a small charge port to the cellpack itself for an external trickle charger or something.

Any help you folks can offer would be greatly appreciated. We've been working our butts off like mad trying to get this bike completed for our first show Jan 17, 2007 and I can put any more of this bike back together until this problem is resolved :(

Thanks everyone!!!


-Adam Hennessy
ERodTech Rides
Knight Time Autoworks
(518)638-8150

[Nightz]

Sound like your resistor divider is limiting your current too much. You need a DC/DC converter to bring your voltage down, then use a series resistor to limit the current.

google "onboard glow driver"

This might work too.
http://www.centralhobbies.com/glow/glow_drivers/prodriver.html
or
http://www.dimensionengineering.com/AnyVolt.htm

-Rocko

[BoxxerSix]

Sound like your resistor divider is limiting your current too much. You need a DC/DC converter to bring your voltage down, then use a series resistor to limit the current.

google "onboard glow driver"

This might work too.
http://www.centralhobbies.com/glow/glow_drivers/prodriver.html
or
http://www.dimensionengineering.com/AnyVolt.htm

-Rocko


Thanks for the quick response. Yes, I was thinking of those DC-DC converters too. Started searching for something that would work in my application but haven't located anything yet. Size is of a particular concern as this picture http://www.ss-graphics.com/_ERodTech%20Rides/slides/2005%20Independant%20Low-Life%20Custom%20Chopper%2068.html
shows what little room I have to play with.

That Anyvolt product is basically what I need. I would need 2 of them to drive the dual plugs due to the 2A current limit of the anyvolt, but the "out of stock" notation doesn't quite work with the time frame. The other cellpack style drivers look to be too large for my fitment issues, although actual dimensions would confirm that.

I'm going to keep searching for a small dc-dc converter or transformer to drop 12v down to something useful in this application

If anyone else has any input please post here :)


Regards,

[MatC]

Or... just use the right value of power resistor? :)

I would guess glow plugs are like lightbulbs... low resistance until they warm up, then their resistance goes up a lot. This makes it really hard to guess what value power resistor you need, because you can't make cold measurements.

Right, some practical solutions:
Get a 2v battery from someplace, fire up the 'plug, and measure the current through it (ie warm current). Call this IGlow (in amps). Eg 2.
Hence you know the series resistance you need: R = 10 / IGlow (because you want to drop 10v). Eg 10/2 = 5 ohms.

Power needed for this is I*V*2 (2 because you need some margin here). Eg 2*10*2 = 40. 40W power res are harder to come by then 10W, but you can put 4 * 10W in series/parallel arrangement to give you the same value with 4* power capacity.

Now, the problem with this is starting power for the plug. PlugPower = I-squared * R.
I-squared is constant-ish at about 4, but resistance changes from (small) to about 1 ohm. So that's 4W when it's warm, but a lot less when cold (because of lower resistance). Hence a 2v source would be best (as Nightz says). Might work anyway though.

Easiest solution to get started is to use 6 glowplugs in series. 2v each, so 12v in series. The major downsides of this are.... they might not all get warm (for reasons as above, they won't all warm up at once).. and if one blows, they all stop working. Try it and see I guess.

Another idea might be to trickle-charge a small 2v battery from your 12v source, and use that to provide the initial warmup current, providing running current from the main battery through a resistor. Simple and cheap. Shout if want more info.

Anyway let us know how you get on, always willing to help anyone crazy enough to try to get flames out of the back of a beautiful chopper like that.

[rc404]

Any help you folks can offer would be greatly appreciated. We've been working our butts off like mad trying to get this bike completed for our first show Jan 17, 2007 and I can put any more of this bike back together until this problem is resolved :(



My first thought was something like this

http://www.uoguelph.ca/~antoon/gadgets/glow.htm

though there probably are simpler circuits using the same concept, 555 for PWM and a MOSFET.

However, since you are in a hurry and collecting components and building a cuircuit takes time, I'd go to a local hobby shop and see what they have in power panels. These are designed to drive glow plugs from 12 V battery. Tear the guts out of it and perhaps with a little judicous hacking you can get down to a size you can use. All the parts you need will be there.

Ed

[BoxxerSix]

Anyway let us know how you get on, always willing to help anyone crazy enough to try to get flames out of the back of a beautiful chopper like that.

:D :D

[Nicetie]

BoxxerSix , Beautiful bike!

Do you know that your fuel will ignite from the glow plug catalyst? I would think
it will need the current supplied for the duration of the burn.

Hope you have resolved this issue by now.

Ken

[Kwok_Yu]

How about this one:
http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXHZE5&P=0

[BoxxerSix]

BoxxerSix , Beautiful bike!

Do you know that your fuel will ignite from the glow plug catalyst? I would think
it will need the current supplied for the duration of the burn.

Hope you have resolved this issue by now.

Ken


I did run a burst of the propane/nitrous mixture directly over an open glow plug held in a fixture(powered by a normal clip on glow ignitor) and blew off a ~six foot purple/blue flame. I'm hoping it works inside the pipe with the engine running. I did the 180* offset/downstream nozzle-to-glow plug setup assuming that as the mixture is injected into the exhaust pipe(2" diameter) it will travel down the pipe a small amount(~1" or so) due to the expelling exhaust gasses. The nitrous/propane bottle pressure is about ~1500psi, so the mixture should theoretically be injected right before, if not directly into the plug.

I was planning on having the plug stay hot/lit as long as the mixture was being injected to keep an ignition source open. Even so, it's really only intended for very short 1-2 flame bursts, otherwise the pretty metallic paint will start looking a bit on the dull side.

I haven't resolved this yet, but I think I'm going to take a simple route right now for the time being and solder my own cell pack to power these plugs. I'll operate the glow circuit through a relay, activated by the same button that activates the nitrous purge solenoid. I found a temporary spot on the underside of the bike that I can mount a small cell style battery pack and relay to heat the plugs, and it accessible enough to pop out dead cell and replace with fresh ones. It'll suit for now so I can get this bike finished for the show and allow me time to get the correct parts I need for a more permanent fix.

I appreciate all the help here you guys have offered. This is a pretty cool site. I have a couple glo-powered HPI's and had a plane back when I was a kid. In the relative near future, I have a project where I want to build an AWD 4-stroke drivetrain for a 1/6th scale Porsche 996 Turbo electric car I have here. I'm a HUGE Porsche enthusiast, drive them(965), build them(stree legal replica 962), and work on them for customers too. Just fitting to have a lifelike RC car to boot right??? Now that I found this site I can harass you guys for all sorts of parts info :D Thanks again!

[Acetronics]

Hi, Boxxer

Our screen Heroes are not the same ... but, have a look, and dream a while

hou could have seen and heard her in Detroit !!!

EVERYTHING works as the original ...

Alain

[Rodney]

Do what most power panels do, build an oscillator that puts out a 1 millisecond pulse every 11 milliseconds (1 millisecond on, 10 milliseconds off) Make the 1 millisecond period adjustable from about 1 to 2 milliseconds. Use this 1 millisecond pulse to gate an FET on to put 12 volts on the glow plug. This works great and will not hurt the plug; just do not let the 1 millisecond pulse get to long or it will burn out the glow plug. There are many circuits for this on the web, just do a little searching for glow plug drivers.

[fhhuber506771]

I think I found the answer to powering the plugs CORRECTLY without having the separate battery pack. Just a switch to activate this device (one per plug... should be able to parallel wire it on the "flame fuel" injection switch) and its "Flame On"

http://www.peakmodel.com/index.php?main_page=product_info&cPath=64_76&products_id=310

$15.80
1. High technology regulator application, output voltage is 1.5V
2. Switching transfer (low heat dissipation)
3. All kinds of 3.5-20V batteries can be used
4. With LED indicator
5. Input reverse protection

***********

I found it searching for the lowest cost source for the Dynam 60 amp brushless ESC. (and this place is $10 each less than any other I found)

[BoxxerSix]

Hi, Boxxer

Our screen Heroes are not the same ... but, have a look, and dream a while

hou could have seen and heard her in Detroit !!!

EVERYTHING works as the original ...

Alain

:D Porsche may be my love for cars, but old Ferrari's are super nice. Especially fully functioning scale replicas. I saw the(a) video of this model running a few weeks ago. I was VERY impressed not by much as the motor or transmission, but super small detail like fully functioning multi piston floating rotor brakes and a complete working analog dash.

The model I want to build is nowhere near that in-depth. Just a "cheap" 1/6th scale ABS bodies 996 Turbo I have here. Full working lights, doors, full interior, etc. More of a large moving display model than an RC car. I want to keep the asthetics as such, but build from scratch an AWD drivetrain/chassi/suspension underneath the existing body and power/gear it using a four stroke OS style airplane glo engine. Something different, more for realism than all out performance in the RC world. Going to build it around the Paris Dakar theme rally Porsches

I think I found the answer to powering the plugs CORRECTLY without having the separate battery pack. Just a switch to activate this device (one per plug... should be able to parallel wire it on the "flame fuel" injection switch) and its "Flame On"

http://www.peakmodel.com/index.php?main_page=product_info&cPath=64_76&products_id=310



***********

I found it searching for the lowest cost source for the Dynam 60 amp brushless ESC. (and this place is $10 each less than any other I found)


This little thing just might work! I could easily modify that module to fit in the allocated space(would need two of them). I made my own style of clip on plug connectors so I won't need that whole length of that long tube style clasp. Thanks for this link, I'm going to call tomorrow!

[fhhuber506771]

Note.... The place has good prices on stuff... but the shipping is a bit high. I ordered the 2 ESC's and a couple of props... $27 shipping. Still cheaper than I could have gotten just the ESC's elsewhere. But you need to use thier shipping cost calcultaor to check.

[Kwok_Yu]

..This little thing just might work! I could easily modify that module to fit in the allocated space(would need two of them). I made my own style of clip on plug connectors so I won't need that whole length of that long tube style clasp. Thanks for this link, I'm going to call tomorrow!
Did you check out the link I posted? No mention of my little thingy. :o

[BoxxerSix]

Did you check out the link I posted? No mention of my little thingy. :o


Opps, I'm sorry I didn't even see your post there. That'll probably work too as long as I can strip the driver circuit from the board and package it smaller. I like the variable voltage output on that driver......allows me to run the plugs a bit on the hot side, despite reducing their life. Hotter = better chance of ignition....