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I got a old RC car + controller, I would like to increase it's range. I did a research and I found a idea here. The idea states:

Here's what you do. Parts: one (1) NPN transistor. Tools: Soldering iron, wire cutters, wire.

Idea: After going over my RC remote with a multimeter I've found that the amplifier(transistor) inside the remote only runs at .2 volts So... using that as a first stage amplifier is a good start. Then, when you connect the 3v from the batteries to your amplifier(transistor) it'll be a 15x gain. So, your transistor has 3 pins C B E connect C to the + terminal either on the PC board or straight to the batteries. B to where the antenna used to connect. And E to the antenna wire. This tripled the range of my New Bright remote control mustang. Also, remember your remote converts it all to a serial message that gets decoded at the end point so it doesn't have to be all that great of signal quality. It can be noisy as hell and it'll still get the message across. Good luck!

So I'm beginner and still I have no idea what I'm doing so I would like to ask about little explanation how I can wire the circuit.

enter image description here

I found in my house a TIP120 transistor. If my schematic is wrong can somebody explain me how to get it working?

PS: Sorry for the bad schema, I wasn't sure how the components between the antena and the transistors are called.

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    \$\begingroup\$ almost certainly you'll be exceeding the transmission power limits for that frequency band and I should add you would be breaking the law. I would also point out that any mod like this would probably incapacitate other RC cars close by so if winning the race by any means is your aim then good luck. \$\endgroup\$ – Andy aka Oct 17 '13 at 16:40
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    \$\begingroup\$ You don't have to change the circuitry at all if you merely improve the antennas of both sides. As @Andyaka points out, you'll probably be exceeding legal limits, though. Right now you probably have cheap antennas on both sides. Use a better antenna on the car, and use a directional antenna on the controller - just remember to keep the controller pointed at the car. That should give you a significant boost in range without a lot of work. \$\endgroup\$ – Adam Davis Oct 17 '13 at 17:42
  • \$\begingroup\$ What if I want to make it extremely high, no matter what the law is? How I should wire it \$\endgroup\$ – Deepsy Oct 17 '13 at 19:25
  • \$\begingroup\$ @Andyaka I don't want to race with it or something, just personal use in home, but I have a really big garden. \$\endgroup\$ – Deepsy Oct 17 '13 at 19:36
  • \$\begingroup\$ Also if I connect the transistor like I showed on the schematic, will it even work? \$\endgroup\$ – Deepsy Oct 17 '13 at 19:57
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The way it is described in the OP's circuit quotation will probably mean it doesn't work because the transistor emitter is connected only to the antenna and there is no mention of a pull-down resistor to properly bias the added transistor.

I'll also say this about the quote. The person writing it has no idea what he is doing or why it works:

  • The existing amplifier only runs at 0.2V - if this is true then it won't be enough to bias the extra transistor stage.
  • Coming up with a statement of "it'll be a 15x gain" is not based on sound reasoning.
  • The author also says "It can be noisy as hell and it'll still get the message across". This indicates to me that he doesn't understand much about radios.

Increasing the power output from the transmitter, as previously said in comments, is probably breaking laws on transmission levels especially if the power (or voltage?) is increased 15 times.

More likely to get a good increase in range (maybe double) is to improve the radio receiver in the car - this won't be illegal.

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  • \$\begingroup\$ Thanks for the nice answer. I'm gonna use this car far away from any civilization, so the law isn't problem, there isn't anything but forest around my house. Is there any way with which I can cheaply improve the radio receiver or transmitter. I'm beginner so "improve the radio receiver" doesn't really mean anything to me, sadly :( so If I increase the voltage thru transistor, I should theoritically increase the range? \$\endgroup\$ – Deepsy Oct 17 '13 at 21:41
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    \$\begingroup\$ @Deepsy What the article suggests is a pile of horse manure realistically and what you may be able to achieve on your own, without circuit diagrams is probably hardly any improvement unless you are lucky. Increasing the AC voltage signal being transmitted is what you want but you have no way of measuring that with a standard multimeter. You'd be working in the dark. Of course modifying the receiver is harder (hence you probably won't try) but it is likely to be the best track to take. Again, circuit diagrams are needed and these are not easy to get hold of. Not all transmitters are the same! \$\endgroup\$ – Andy aka Oct 17 '13 at 21:53
  • \$\begingroup\$ Just one more question. How I can test how much I increased the range, without going out and testing it "manually" every time? And what's the name of this component i.imgur.com/7GLwNfM.png \$\endgroup\$ – Deepsy Oct 19 '13 at 11:45
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    \$\begingroup\$ it looks like a capacitor. Improvement testing is best done by a distance comparison. Put the car on a stand to stop it driving off and activate the throttle is my best guess. \$\endgroup\$ – Andy aka Oct 19 '13 at 12:06

protected by Dave Tweed Jul 11 '14 at 18:50

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