Author Topic: Ignition engines (Read 1306 times)

Mike_Fitzgerald · « **on:** January 22, 2024, 04:03:51 PM »

Can anyone help me contact Jim Lee? I asked Jim Hoffman and he told me to look up Jim Lee on S/H ...I have a question about ignition coils...

Tnx Mike

bill bischoff · « **Reply #1 on:** January 22, 2024, 04:17:51 PM »

leemachineshop.com

Dan McEntee · « **Reply #2 on:** January 22, 2024, 05:22:15 PM »

Jim is a member here also, and you can PM him and email him through the forums. He just replied to the thread that Bob Hunt has with all the old photos.
Type at you later,
Dan McEntee

Jim Kraft · « **Reply #3 on:** January 23, 2024, 12:27:25 PM »

I fly a lot of ignition engines. I can probably answer your question if you cannot get a hold of Jim Lee.

Robert Zambelli · « **Reply #4 on:** January 23, 2024, 01:08:12 PM »

And I can help also.
Bob Z.

Mike_Fitzgerald · « **Reply #5 on:** January 23, 2024, 05:37:23 PM »

Thanks for the replies...I sent an email to Jim Lee but didn't get a reply...Here's the deal...I have flown many ignition engines but it's been awhile...I might have lost my touch...I have two coils but can't get either of them to produce a spark at the plug...Both coils appear to have been ridden hard and put away wet....The coils have continuity on the primary windings and the secondary windings appear to have continuity as well...I have tried 2, 3 and 4 cells ...Points are set to .015" ...Is there any way to test these coils?? They seem to have become as scarce as hens teeth...Any info greatly appreciated!

Tnx Mike ...Flying Control Line for over 70 years

Jim Kraft · « **Reply #6 on:** January 23, 2024, 06:24:49 PM »

Hi Mike. Are you using a condenser or a transistor ignition of some sort? Sounds like your coils are OK. They should only be a few ohms across the primary, and some where around 4600 to 6500 ohms on the secondary.

But I have had coils that check good but do not work. Rare though. An I have a Smith Fire Cracker coil that only measures 3600 ohms on the secondary, but throws a very hot spark.

James Lee · « **Reply #7 on:** January 23, 2024, 06:35:38 PM »

Mike
Also, check all your wiring. A bad connection can ruin your day.
Thanks
Jim

Mike_Fitzgerald · « **Reply #8 on:** January 24, 2024, 11:40:57 AM »

'Morning all...Primaries read about 1 ohm and the secondary windings about 4500..Not using a transistor .... Just plain 0le ignition circuit...WRT the condenser/capacitor...I thought the only purpose of the capacitor was to prevent arcing at the points...yes/no???

Tnx Mike

James Lee · « **Reply #9 on:** January 24, 2024, 11:47:43 AM »

Jim Kraft · « **Reply #10 on:** January 24, 2024, 05:10:02 PM »

The capacitor also boosts the charge to the coil and you will get no spark without one. And they do go bad sometimes.

Mike_Fitzgerald · « **Reply #11 on:** January 24, 2024, 05:36:18 PM »

Can you advise as to what is the optimum vale for the capacitor?
Tnx Mike

Dave Harmon · « **Reply #12 on:** January 24, 2024, 06:03:45 PM »

Quote from: Mike_Fitzgerald on January 22, 2024, 04:03:51 PM

Can anyone help me contact Jim Lee? I asked Jim Hoffman and he told me to look up Jim Lee on S/H ...I have a question about ignition coils...

Tnx Mike

The capacitor might be shorted....you can remove one lead of the cap and try again.

Jim Kraft · « **Reply #13 on:** January 25, 2024, 04:24:41 AM »

Capacitor value is .01-400v. or .1k at 400 volts. If it is shorted you can read it with your ohm meter. You will get no spark without the capacitor.

In all the instructions I have with my engines the only one I have that gives the capacitor value is the Atwood Super Champion. Any good electronic store will have them. Or you can use automotive capacitors but they are a little bulky.

The electronic store capacitors are not a can type, but work the same. They just have to go between the point lead and ground.

FLOYD CARTER · « **Reply #14 on:** January 25, 2024, 12:55:20 PM »

I(f your capacitor (condenser) is the small metal job with a tab for mounting, it is probably n.g. These old capacitors are "paper" dielectric and not sealed. They go "dry" with age. Check if your contact points spark a lot while trying to start the engine. Sparks indicate faulty capacitor.

You might try a capacitor meant for motorcycle, lawnmower, etc.

If all else fails, I have a test rig which tests spark coils at 7500 RPM. You can send the coil, and I would be glad to give it a good test (with photos)

Mike_Fitzgerald · « **Reply #15 on:** January 27, 2024, 10:44:19 AM »

Thanks for all the replies....Found the problem...A bad brand new capacitor....One last request (on this subject) ...Anyone know where I can find a schematic of a transistor ignition system?...I've searched the net but find nothing with component values etc...Tnx again for all the input...

Mike

Dan McEntee · « **Reply #16 on:** January 27, 2024, 11:57:38 AM »

Quote from: Mike_Fitzgerald on January 27, 2024, 10:44:19 AM

Thanks for all the replies....Found the problem...A bad brand new capacitor....One last request (on this subject) ...Anyone know where I can find a schematic of a transistor ignition system?...I've searched the net but find nothing with component values etc...Tnx again for all the input...

Mike

If Floyd Carter sees this, I think he can help as he produced them. I think there is still a vendor out there that offers them but but I'm a little brain dead this morning, a little more than usual!! Just remembered that the late Don Hutchinson made them also. If he offered a schematic, some one may have o be out there.

Type at you later,
Dan McEntee

Jim Kraft · « **Reply #17 on:** January 27, 2024, 03:06:19 PM »

Here is simple one transistor circuit that works well and eliminates the capacitor. You do not need the resistor in the plug lead as it is only used for keeping the interference out of the RC planes.

It uses a PNP transistor of between 5 and 10 amps. I have used audio transistors that work well. You do need the 20 ohm resistor in the point lead.

FLOYD CARTER · « **Reply #18 on:** January 27, 2024, 03:51:36 PM »

If you are not familiar with working with power transistors, it is easy to get the wrong one!

Transistor coil driver units are still available from

Larry Davidson
www.modelflight.com/larrydavidson?html

Larry carries the Model TIM-4 transistor coil driver, which I produce and wholesale out to Larry.

Jim Kraft · « **Reply #19 on:** January 28, 2024, 12:26:17 PM »

I will vouch for Floyds coil driver as they work great. Since everything is on the small board they are easy to hook up and will give you a good spark.

Dan McEntee · « **Reply #20 on:** January 28, 2024, 12:37:10 PM »

Quote from: FLOYD CARTER on January 27, 2024, 03:51:36 PM

If you are not familiar with working with power transistors, it is easy to get the wrong one!

Transistor coil driver units are still available from

Larry Davidson
www.modelflight.com/larrydavidson?html

Larry carries the Model TIM-4 transistor coil driver, which I produce and wholesale out to Larry.

Larry Davidson is the name I couldn't think of in my previous posts.

Type at you later,
Dan McEntee