Contactless key

In this article I will tell you how to make a simple and reliable version of a contactless key.
To begin with, I’ll explain what this key is, the point is that there is a transmitter on a battery and a receiver built into the device we need; we bring the transmitter to the device, and it starts working. The big disadvantage of our installation is the range, it is approximately 5 cm.
Before assembling the device, consider the diagram


Transmitter.
It is a conventional high-frequency generator (HHF) based on a block generator. I used the KT930 transistor, and the KT315 and all other npn transistors of the 3,6,9 series are perfect, basically they are all generator ones. The circuit can also be powered from a 1.5 volt battery, but the higher the supply voltage, the greater the range. Another flaw of this scheme is that the transmitter starts only after short-circuiting the base and collector, but it’s not difficult to make a start button.
Receiver.
Coil L3 comes into resonance with the transmitter, as a result of which an alternating current is induced in it, which is rectified and opens transistor T2 (MP20OS) and by means of all these machinations, relay K1 is activated to which you can now connect anything you like.
Enough theory, let's move on to practice.
Here is the required set of parts


And another relay.
We will also start the assembly with the transmitter, first of all we will wind the coil, take a round frame with a diameter of 5 cm and wind a wire with a diameter of 0.1 to 0.6 mm onto it; the thicker the wire, the greater the current consumption.


for L1 and L3 60 turns for L2 30 turns. After this, we solder the windings according to the circuit with the transistor and place one on top of the other


And we get a rather interesting setup if we connect coil L3 directly to the terminals Light-emitting diode You can get an amazing effect; you can even call it wireless energy transfer.


You can check it in the same way; if it doesn’t work, I repeat, close and open the collector and base, or turn over one of the transmitter windings, just grab it with your hand and turn it over. The field is also pierced by 338 sheets of glossy paper


Therefore, the receiver can be easily hidden in the case of any device, only the case should not be made of metal


All that remains is to add the relays and electronics.
You can find a lot of applications for this device; it can be built into a PC case, but it is advisable to shield the receiver from the motherboard; this can affect the operation of both the receiver and the computer. I think there will definitely be a use for such a device. If not, then you can leave it Light-emitting diode attach the transmitter, for example, under the table, and put the receiving coil on the table, you will also get a very funny device.
Good luck to those wishing to repeat!
P.S. video with a visual demonstration of the receiver and the operation of the device



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Comments (21)
  1. ENDY
    #1 ENDY Guests 13 August 2011 23:55
    0
    I don’t even understand what’s on the battery diagram?
    NOTFRONT, I don’t know about T2, but the LED doesn’t care, the current is low.
    feelloff, this is not bullshit, but wireless energy transfer.
    This thing, or rather its prototype, was invented by N. Tesla. And what’s more, this thing is harmful to health (its range of action)
  2. feelloff
    #2 feelloff Guests 13 August 2011 17:30
    1
    The article is called CONTACTLESS KEY, a diagram of a CONTACTLESS KEY is given, and at the end it turned out to be some kind of bullshit with a light bulb PAY POINTS TO THE AUTHOR!!! smilesmilesmilesmile
  3. NOTFRONT
    #3 NOTFRONT Guests 13 August 2011 17:18
    0
    Who includes T2 in the circuit? it will burn out, a resistor is needed between the base of the transistor and the rectifier assembly. Yes and Light-emitting diode you need to turn it on through a resistor!
  4. feelloff
    #4 feelloff Guests 21 August 2011 16:27
    0
    Yes you are a genius!!! smilesmilesmilesmile Wireless energy transmission up to 1 centimeter. I advise you to immediately patent it before someone else does it! biggrinbiggrinbiggrinbiggrin
  5. Veent
    #5 Veent Guests 21 August 2011 21:22
    0
    This is just an experiment, at 1.5 V 4 cm, imagine what will happen if you run at least 220 V or 750 kV like at a power plant, and you can supply 10 V through one wire for about 25-30 m, depending on the source. Sometimes it’s more interesting to square a circle than to assemble amplifiers, multivibrators, and thermometers with clocks. cool
  6. ANONIM
    #6 ANONIM Guests 24 August 2011 21:59
    0
    What if you increase the number of turns? Is it possible to increase the range?
  7. Veent
    #7 Veent Guests August 25, 2011 09:18
    0
    It will increase, just don’t deviate from the proportions
  8. VVLAD
    #8 VVLAD Guests August 30, 2011 11:04
    0
    But what if L1 and L3 each have 120 turns of 0.2mm wire, and L2 60 turns of the same wire, the range of action will be 8 cm. True or not?
  9. Danbaz
    #9 Danbaz Guests 26 September 2011 20:30
    2
    Actually, it’s not clear why all this? :( a banal reed switch and a magnet - that’s the key for you. biggrin no less contactless.
  10. Veent
    #10 Veent Guests 26 September 2011 22:11
    1
    I agree, as a key it’s effective but nothing new
    But regarding electricity without a wire, a reed switch can’t do that