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Using a 3 pin accessory without a controller.

Using a 3 pin accessory without a controller.

Old 06-15-2024, 04:16 PM
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Default Using a 3 pin accessory without a controller.

Hi everyone, new to the forums, but have been an amateur with rc for awhile, and I had a hopefully simple but kind of oddball question.

I am looking into getting a 1/10 emergency flasher lightbar that uses a 3 pin to be hooked up to and controlled by CH3, but does anyone know how to wire one of these accessories up to a standalone battery, possibly with a switch? I understand I need positive and negative on the black and red, but is there a way to still control the accessory, by wiring in a switch?


Thanks for any help, Iím trying to make a police truck for my son and would love to ad flashing lights, and these light bars look perfect, but I would need to have it on a separate battery and donít know if I could just feed it power and control it a switch and expect it to flash, or if Iíll need to spoof the controller to cycle through the different flashing modes.

I canít post the listing to what Iím looking at specifically, but I believe that any CH3 accessory would essentially function the same, and just need power and whatever that mystery wire feeds to it.
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Old 06-16-2024, 12:15 PM
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Originally Posted by PowerSet
Hi everyone, new to the forums, but have been an amateur with rc for awhile, and I had a hopefully simple but kind of oddball question.

Small update, I ordered a handful of the lightbars (Iím making 3 trucks in total), Iím sure I can make them work,but I figure I would post updates anyway for the future, since it seems like thereís little/no info about it available. Worst case scenario, Iíll just use the plastic shell and replace the electronics and wire them up myself to flash, but hopefully I can trigger them to work the same was as if they were being controlled in an rc.

I would at least attach a picture, but I canít yet as a new member, but this is just a generic part available through ebay, amazon, Ali express etc if you search for ďrc flashing police light barĒ
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Old 06-16-2024, 03:54 PM
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I looked at half a dozen listings and none of them had any detailed information. It's impossible to determine from that what their behaviour will be. I would *assume* that they will have a default sequence/flashing in the absence of a PWM signal from the receiver, but the only way to know will be to test them. About 12 years ago I built an F1 safety car and used a police light bar on the roof, but it was "dumb" in that it only have wires for power. It did have a separate button to press for alternate light patterns.

If they absolutely required a PWM input, and space wasn't too much of an issue, I'd buy a cheap servo tester (~$6), strip it down and hook that up.
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Old 06-17-2024, 05:39 AM
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Originally Posted by PDR
I looked at half a dozen listings and none of them had any detailed information. It's impossible to determine from that what their behaviour will be. I would *assume* that they will have a default sequence/flashing in the absence of a PWM signal from the receiver, but the only way to know will be to test them. About 12 years ago I built an F1 safety car and used a police light bar on the roof, but it was "dumb" in that it only have wires for power. It did have a separate button to press for alternate light patterns.

If they absolutely required a PWM input, and space wasn't too much of an issue, I'd buy a cheap servo tester (~$6), strip it down and hook that up.
Thank you for the reply, thatís exactly what I was looking for for info,I have never used a servo tester, but if that would be able to spoof the pwm input if itís needed, then thatís a huge help. I donít know anything about how the pwm input works, and was unsure if it essentially just controls power to whatever device itís for.

I did figure that the only way to be sure would be getting and testing some, but I wasnít sure if anyone had a suggestion for spoofing the pwm signal if necessary. Thanks!
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Old 06-17-2024, 07:17 PM
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You could also get one of many small Arduino-compatible boards and very easily program them to output a fixed or varied signal. For beginner purposes, the standard Servo library makes this pretty simple. Just make sure that the board is happy with the voltage you want to give it.

The cheap servo tester would be a simple off-the-shelf approach.
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Old 06-20-2024, 11:19 PM
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Originally Posted by PDR
You could also get one of many small Arduino-compatible boards and very easily program them to output a fixed or varied signal. For beginner purposes, the standard Servo library makes this pretty simple. Just make sure that the board is happy with the voltage you want to give it.

The cheap servo tester would be a simple off-the-shelf approach.

I appreciate the suggestion, but Iím definitely not trying to add an arduino or more boards, Iím up to about $30-$35 per truck already and Iím making 3 or 4.

Fortunately the lightbar is set up so that if it has power, it flashes and just cycles through the different modes, which is more than good enough for my current needs.

I am waiting on a servo tester and will mess around with the light bars and see if I can choose specific flash modes with a pwm signal, or if itís just on or off, and thatís the only way the lights function.

In the meantime, Iím just pumped that rc modifications are popular enough that I was able to easily find these light bars online! The lights are like the icing on the cake!
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Old 06-21-2024, 05:24 AM
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Glad to hear you're having fun! If you find the servo tester does cool things, a cheap Arduino board is likely available for under $5 in a lot of places and you can program it for free to emulate a servo signal.

PS: It's entirely possible to go nuts with this stuff for endless fun and I'm all for over-the-top-ness. This is a custom setup controlled via a spare channel on the radio:
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Old 06-21-2024, 10:15 AM
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I definitely have some plans that will involve adding arduinos into the mix, this project just spiraled out of control from ďIll get some trucks and make decals for themĒ to ďOkay, these trucks are going to have flashing lights, four different audio tracks with their own buttons, and a rechargeable batteryĒ

Im literally making custom paw patrol trucks for my toddler lol
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