Mar 31, 2014
This post is a response to the project named: RF Radiation Detector.
I got an e-mail from electronics hobbyist who did not allow me to mention his name but only his email: email@example.com, located around Chennai in South India. He enjoyed making this project and tested it around his home. He searched youtube for ‘RF Detector’ and he found my instructions in my video(www.youtube.com/watch?v=xgIL81VSKX4).
Just wanted to let you know that your RF detector circuit is awesome… Your circuit is the simplest I have yet found and your instructions are great. I shared my findings and pic with friends. It generated quite some interest… This circuit has been great fun to make and test around my home…
His Research: His main interest was to measure the RF discharge from everyday electronics, because he was worried about the radiation risk. Surprisingly, he found that the RF coming from tube lights, power adapters, monitors, etc is much higher than mobile phones. Also, he found that mobile phones radiate more when call-negotiation is happening with the cell tower. Once call is in progress, RF levels fall substantially. He was able to show that some popular cheap brands (like Micromax) are actually radiating substantially more than good brands like Nokia and Samsung. He found that his microwave was actually shielded quite well. He was not able to pick up any Radio frequency from it. He was also not able to pick up ambient Radio frequency from the cell tower near his house, which he was worried about. Of course, it’s possible that his antenna design may have a limited frequency response. I suppose at some point we can calibrate the antenna too. Laptops can also radiate RF, which is more than mobile phones. iPhones radiate a lot too. They do it in approx 5 to 10 second bursts when not in use. When call is being received or in progress, they behave like any other phone, except with much more radiation. This is a surprise for me.
Project Design: Below is the picture of his circuit which he attached in his email upon my request. He has used Multi-meter at output(LED) of this circuit. LED did not work for him at all, at first he thought he had made an error, but later he realized and wired the multi-meter and was able to see the circuit work. His antenna is about 1 meter long. He tried different shapes and finally settled on the “Wound Antenna”, as shown in the figure. It has conducting wire wounded around a plastic cup in a form of helix. The capacitors used are not polyester capacitors like the one on rookie’s, But they have the same specs and do the job perfectly.
Further Planning: He is looking forward to make the circuit a little more portable with permanent soldering and with it’s own numeric readout. So, he is planning to add a 3-digit digital Voltmeter to it (0 to 30 volts range). Of course, for that he will need a battery to drive the digital voltmeter display. Eventually planning to solder the whole thing to a PCB(Printed Circuit Board), make the antenna more permanent (and perhaps substitute enameled wire instead of breadboard leads, and put the whole thing in a casing. That way he won’t need to spend upwards for $100 for the RF detector he always wanted.