jessh1969

My Feedback: (1)

I have been refinishing my GP ju-87 for a couple months, and have added some new wrinkles...It is glassed, has a bomb drop, and I have built an onboard glow system. I wired and tested the system last night, and it works great. I do, want to verify something though....In the attached drawing, I am using the remote glow jack already in place as a charging jack to the C cell. As long as the arming switch is "off" then I can plug the charger into the jack and charge the battery w/o lighting the plug, right?! Or, if I want to light the plug via the charging jack, then I can "arm" the system, and it will light? Everything is wired up and working correctly except the charging loop. Currently I have it set up with a radio mix to close the second switch when the throttle is below 1/4, or I can close the switch manually by a switch.

jessh1969

My Feedback: (1)

try to get image again.....

ho2zoo

My Feedback: (5)

I have built a couple of glow driver systems very similar to yours. Looks like it should work, but I don't think you will be able to light the plug just using the charging jack. It would need to have both the arming switch and the servo switch turned on to work, and then it's going to be using power from both the battery and the charging jack at the same time. I don't know what effect that would have on whatever you have connected to the charging jack. Perhaps some of the electrical engineers around here could comment...

jessh1969

My Feedback: (1)

Yes, I realized I will have to have both switches closed to light the plug from the charging jack. I did that so I could open the connection on the arming switch and just charge the battery. What I was thinking though...in the event that the battery was low/dead at the field, I can close the switches and then use the charging jack to light the plug, right? I was just not sure about the low/dead battery in the circuit being too much resistance between the jack and the plug. Thanks for the input!

Meschmidt

My Feedback: (15)

You need to really do a good radio check before you fly this system. I made one also a few years ago similar to your setup and it intermittently caused radio interference while it was energized. Something about the EMF of the circut causes this interference. If I remember right some sort of a diode or a choke has to be in this circut to eliminate this. Maybe someone more knowledgeable will respond and refresh my memory. Paul

jessh1969

My Feedback: (1)

Paul,
Thanks for the warning!. Since I have done a complete "remodel" on this plane, she will get extensive preflight tests . I will do a good range check with it running and off to see if I can find any bugs. What about one of those small capacitors that they include with electric motors? Isn't that what they are for? Besides range checks, how can you check for EMI? Maybe a scanner on/close to your channel?

Thanks!

Jess

feihu-RCU

Using a servo switch set at 1/4 throttle is asking for trouble, as Meschmidt has pointed out. I would do away with the throttle control and control a servo on-off switch from the transmitter. And you don't need the arming switch. With these changes, you turn the glow plug on and off from the transmitter and you can parallel the on-board cell for starting if necessary, or turn the glow plug off and just charge the on-board cell. You have to set up the switch so that it is off when the transmitter is off.
I use a 2400 mah cell for starting as well since the engine is cowled in and plug not accessable for starting.

feihu

ljhmc

I saw your drawing and thought of the enterprise I am finishing up. I have done close to the same thing. One C cell connected to a remote glow line and between one lead I have placed a remote RC switch on channel 8 on my receiver. I like the idea of using the throttel at 1/4 throw to turn it on and off. I will give it a try this week.

THANKS for the great thought I forgot about... the throttel

Lawrence

feihu-RCU

I'll repeat! "Using a servo switch set at 1/4 throttle is asking for trouble", but you may get away with it.

feihu

jessh1969

My Feedback: (1)

Why? Whats the difference between that and switching it on from the transmitter? I can do either with my current setup. Thats just always what I have heard....have your onboard glow turn on at and below 1/4 throttle. I don't fly around at 1/4 or below...thats used mainly during landing, which is also when I would switch it on from the transmitter. Not be factious, I just thought I was following the common practice.

thanks for the help!

Jess

feihu-RCU

Jess:
Speaking from my experiences, switching on-off from the transmitter can cause a single glitch (radio interference/EMI); whereas on approach for landing, if you happen to stop at the 1/4 throttle setting, the servo can oscillate on and off and cause suficient EMI to momentarily lose control. The vuneronability of lower altitude and speed on approach with momentary loss of control could lead to an unusual airplane position from which you may not be able to recover.
I have seen the glitching on my model on the ground (and that was enough for me); and I have seen a near loss of an airplane that was believed to be caused by such EMI, but luckily no crash.
I understand that some flyers have good luck with the commercial systems, so they all can't be bad, and I'm sure there are others who have good luck with their own systems.
Sorry if I came on too strong about this thing, but I just don't like to see anyone crash their airplane!
feihu

jessh1969

My Feedback: (1)

No, not too strong at all! I appreciate the input. I just didn't understand the difference between running it as either a single switch or a mix. If I am understanding you correctly, the problem would occur when I throttled back to exactly 1/4...the problem being that it would be switching on and off because I was "close" to the threshold? I can see what you mean. I'll take that into consideration for sure. I may do some tests at altitude and see if I have any problems. I have run it on the ground and no problems in a range check so far. BUT, its not that big a deal to turn off the mix and just flip the switch when I want the glow plug lit. Thanks for the input!

Jess

jc286006

My Feedback: (3)

if your wanting to build your own on board glow driver system look into the optiglow II system it works great and you can adjust the on -off point through a pot on the board ive built a few of them and they work great the only draw back is getting the printed curcuit boards made if you dont want to invest in the supplies to do them yourself just do a search for optiglow II

ljhmc

I tried that once and had the adress to write to to get the board and parts to make it myself. never got a return message. Gave up after I could not contact the guy.

C cell is still the cheap way and the use of a remote switch is still a good run on this idea.

Thanks for the info

Lawrence
Omaha