Hello, i am new to electronics. I have a basic knowledge of electronic components and how they work. But i lack the knowledge of calculations and applying the right components with propper values.
I have constructed a wireless oscilating electromagnet. Im using a 9v 555 pulse module to send data to a 433mhz rf transmitter. I have got this end of the circuit to function quite well. But the recieiving end not so much. The 433mhz receiver is 5v. So im using a 7805 voltage regulator to step down voltage from 9v battery. Then the data from the receiver is connected to a 1k ohm resistor then to the base of a tip120 darlington transistor. The reason im using a darlington is because i want as much current as possible flowing through the EM coil. Everything works i just have a few issues. I cant get a full range of adjustment of frequency with the 555 pulse module. Im not getting enough current through the coil. Sometimes the darlington transistor gets hot. And the permanent magnet and the EM coil make this god awful screetching noise when its pulsing. It sounds like a tuning fork and i can actually feel the permanent magnet vibrating at high frequency. Ive tried hooking up more 9v batteries in parralell to boost the current but then i have problems with overheating the transistor. I was under the impression that a transistor acts as an amplifier as well as a switch. So why is it that when i hook the EM coil directly the the batteries i get the amount of current i want. But when the EM coil in wired in the pulsing circuit with the same amount of batteries the strength of EM field is less? Shouldnt the darlington transistor amplify the current? I know there is alot that im missing. Would really appreciate any help i can get. Thanks!
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