Ref the above at http://www.rcgroups.com/forums/showt...ry#post2947786


The circuit diagram in post #7 looks simple enough for even me to handle. However, I know very little about solid state devices, and I am wondering about the voltages quoted in post #5, (3.05 v for the lithium-ion battery). I assume I can use a single lipo cell from a junked 3s pack, but it has more like 4+ v per cell when fully charged.

Does that make the output 4.2-1.8=2.4v which is too much for the glow plug. Should I put a variable resistor (somewhere?). I can get the LM388 here, cheap, and it has an adjustable output of 1.2-33v.

Or should I put a fixed resistor somewhere, to simplify and make sure the output is fixed, not inadvertently bumped too high. But then as the battery volts drop, the output would also drop, I think, to below what is needed for glow plug power.

Well when you realise a Lithium Ion battery is 3.6v nominal, you do wonder if the rest of the info is good.

Much easier to simply use a single Sub-C size Ni-Cad or Ni-MH cell. Less weight, no need for resistors or anything else, and they can be found now rated at ~2000mAh for just a couple of dollars. Just my opinion.......

Are you trying to rig a glow driver for starting your plane, or an on-board glow driver to keep the plug hot?

+1,
A glow ignitor using a sub "C" Nicd cell is the embodiment of K.I.S.S
Pete

Using resistors, diodes or a linear regulator you will be wasting over half of the power from a lipo when using it for a glow driver. Using some form of PWM is really the only good way if you want to use a lipo to drive a glow plug. If not then go with NICAD or NIMH like the others said.

I have found some old, nameless, brandless, AA nimh 1800 mah cells in my box of old batteries which can light the fire just fine, so I dont think I will bother with anything more complicated.

I was recently reminded of the importance of the K.I.S.S. principle at our field. A friend had a brand-new plane, a Hangar 9 Katana with an OS 1.20 4-stroke on it, very nice, but my buddy was having some trouble with it, sometimes when he turned it on it came on OK, other times it didn't. He asked me to look at it, and I discovered that some of the other guys in our club had convinced him he needed to go with an A123 pack, why I don't know because he never flys his planes that much or that often in the same day, but he followed their "advice". Of course, the 2-cell A123 pack required a voltage regulator, and they also convinced him to use redundant switches, etc. The wiring in this plane looked like the space shuttle, and we didn't know if the problem was a switch, the battery pack, the regulator, or what. In trying to troubleshoot the problem, I suggested he go back to the basics, and offered him a fully charged Ni-Mh pack I had in my flight box to start eliminating possible problems. He refused, I guess that was too old-fashioned for him, and he continued to mess with his system. Later that day he flew the plane with the system he had still in it, and on the maiden flight it made 1/2 a lap around the field, stopped responding to the transmitter, and went in wide open in a shallow dive. The debris field was 100 feet long.

We eventually found out that the regulator was the problem. But this particular plane didn't need all that extra weight or complicated stuff. All he needed was a good battery pack and blue skies. Too bad.

"Of course, the 2-cell A123 pack required a voltage regulator"
Not if the servos are rated for 5 cell Nimh operation
Pete

+1 for Dave ...

regulators are most of time too weak to handle the servos peak current draw, and/or are not able to dissipate enough heat ... some measures I recently made have shown peak currents really are impressive, and with the use of " ordinary" wiring, often cause receivers resets ...

I give you a link to the " voltspy " device : purpose is to measure voltage @ receiver plugs, and catches the minimum reached voltage ...

http://www.modelisme.com/forum/1845101-post46.html

the last software version also gives flight time before dangerous voltage reached ... ( upon request ! )

Surprises guaranteed !!!

Alain

Originally Posted by Acetronics;20874132

I give you a link to the " voltspy " device : purpose is to measure voltage [B

@ receiver plugs[/B], and catches the minimum reached voltage ...

http://www.modelisme.com/forum/1845101-post46.html

the last software version also gives flight time before dangerous voltage reached ... ( upon request ! )

Surprises guaranteed !!!

Alain

Surprised me, that's for sure! That links to a site in le francaise. Moi non parlai francaise! or something like that!!

I did delete to content.
It was't topic related, sorry.

Originally Posted by DL8698

Surprised me, that's for sure! That links to a site in le francaise. Moi non parlai francaise! or something like that!!

Hi,

I went to Singapore some years ago ... but still do not speak Chinese or Malay ...
!!!

Seriously ... I'm French ... this explains that ...

If you need some details, do not hesitate to ask for ... I'll answer you in English

Alain

PS; Even Frenchies can deal with model electronics ...

Originally Posted by Acetronics

Hi,

I went to Singapore some years ago ... but still do not speak Chinese or Malay ...
!!!

Seriously ... I'm French ... this explains that ...

If you need some details, do not hesitate to ask for ... I'll answer you in English

Alain

PS; Even Frenchies can deal with model electronics ...

No offence meant. I did try to learn french (optional subject), long, long ago in school, but gave up after a couple of months. Very hard language to learn! Male and female for everything! And the pronounciation was very hard to master.

French 'aint hard to learn, all ya gotta do is add a "voo" to the end of everything.

Hi, Dave

That's too simple to be fine ... let's see :

if I add voo to "Dave" ... for example ... I get Davooo.

And here, Davoooo is the gentle name for Dave - the - gay ...

...

TRUE !!!

Alain