Simple Problem, I'm Stumped... Please help!

[hibbs]

Hello all,

So I've tried to devise a simple way of connecting/disconnecting my LED circiut from the body and the chassis (to the receiver).


-I have the body wired up and tied into a pair of contacts using deans connector parts. Connecting a 9V battery to the body lights up all LED lights perfectly.

-I have the receiver switch wired up to produce power from the receiver that turns on/off by the radio. It is wired up and I have a test LED that demonstrates that the switch works perfectly. I place the test LED onto the contacts and the radio will switch it off. Pictured are the receiver switch (hobby king)
at top, the receiver middle and my contact with red test LED shining.

Both parts work fine separately. I've tried to hold the connectors together from the chassis to the body (not just resting them one each other but actually pressing them together) and tried to reverse the pos/neg to ensure I didn't wire one up wrong making the pos/neg backwards.

Here is a pic of how it contacts to allow for easy connecting/disconnecting. The contacts just rest on one another and require no plugging or unplugging to remove or install the body. I had it wired up with a 9V before wiring it into the receiver switch to test and make sure everything worked. It did great. It's not an issue of the contacts not touching well because I've removed the contact from the velcro body mount and held it tight to the body contacts to ensure good connection. It's also not a short as both components work great alone. I'm very frustrated and hoping one of the forum electronic wizards can help me fix this. I don't want to go back to the stone age method of plugging it in...

The only thing I can figure is there isn't enough voltage to push the light circuit? I don't want to bump the BEC to 9v for fear of damaging the receiver. both individual parts work fine but when joining them, it fails. I'm so confused.... please help me...

 

[Eric0424]

So you're saying it works fine with 9v, but not with the standard 6v from the BEC. Have you tested it at 7.4v yet? Have you tested the LED's on the body at 6v?

Not knowing what specific LED's you have, it does sound like voltage issue. Try running 6v to the body, if they don't light up then you need to step up the voltage.

 

[hibbs]

So I can't leave it alone. I'm thinking it's a voltage problem. I set up a AA cage with 4 AA batteries (6.0V) and it wouldn't light the single test LED either with 100 ohm resistor or directly to the LED. I soldered up the lights with a 100 ohm resistor for each pair of 2 lights at the front end of the truck for the headlight and side marker. At the rear I used a 100 ohm resistor for each set of 3 lights in the rear taillights. I'm thinking that's too much resistance for the 7.2V I have the BEC set at. I'm going to try to solder the lights directly and use a 100 ohm resistor for the entire front and 100 ohm resistor for the rear set. So the front 4 lights as a series and the rear 6 as a series. Each with 100 ohm resistance for the sets. Hopefully this reduces the resistance to allow for 7.2V to push the lights. I'm fumbling in the dark here guys...lol

 

[hibbs]

So you're saying it works fine with 9v, but not with the standard 6v from the BEC. Have you tested it at 7.4v yet? Have you tested the LED's on the body at 6v?

Not knowing what specific LED's you have, it does sound like voltage issue. Try running 6v to the body, if they don't light up then you need to step up the voltage.

I'm with you Eric. Thanks for the help. I don't think I can step up the voltage to the receiver because the max the servo can handle is 7.4 and I don't know the max for the receiver but it's probably not 9v. I don't want to cook a $50 receiver. I'm going to try to reduce the resistance instead... I had my last 2 trucks running off the BEC with the same receiver switch at 7.2V so I'm kinda confused as to why it's a problem with this setup...?

 

[sf2000xj]

Sounds to me like the receiver voltage isn't high enough to run the leds. What are you running as far as battery pack? Might want to just wire the chassis side to your battery connector instead of trying to pull voltage from the receiver.

 

[hibbs]

Sounds to me like the receiver voltage isn't high enough to run the leds. What are you running as far as battery pack? Might want to just wire the chassis side to your battery connector instead of trying to pull voltage from the receiver.

Ok wow I didn't realize you could do that. I'll have to try it. I'm running 4s so it might be too much. Might have to use higher resistors. Thanks for the idea!

 

[sf2000xj]

Ok wow I didn't realize you could do that. I'll have to try it. I'm running 4s so it might be too much. Might have to use higher resistors. Thanks for the idea!

Ya that's a lot of voltage if you were running 2s you'd probably be OK but 4s your going to want to get the voltage down or you'll burn them up

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[hibbs]

So looking at my wiring I think I made the circuits too large with groups of 4 or 6 lights. I tried to make the wiring simpler but I think I messed it up. I'm hoping to be able to cut the shoe goo out without making a huge mess of it. I tested it with a 9v battery and assumed I was good to go. I ordered new led bulbs and I'm going to re wire the whole thing and test it as I go on the 7.2v output from the BEC. hopefully that fixes it. This should be easy but I'm struggling with it haha. Thanks for the help everyone.

 

[smm1325]

I've used this site with great success to design and build led light arrays. http://led.linear1.org/led.wiz


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