らじおんRadio made by OP-AMP Many friends said to me that my products are unique. I will show you the very unique circuit. See fig 1! This is a radio. Can you believe it? See fig 2! You will understand this is normal superheterodyne radio receiver. It does not use any coils. It uses a filter and oscillator made by OP-AMP. See fig 5! Convertor is constructed by a OP-AMP detector. When the plus input is positive , it pass through the antenna signal. When the plus input is negative , it does not pass through the antenna signal. Therefore antenna signal is converted to 40kHz IF signal. IF filter is constructed by the low pass filter. Q of it is higher than 1. So it works as a band pass filter. See fig 4! IF-AMP is a normal non-inverted-AMP. Detector is OP-AMP detector. You can use a normal diode detector indicated in fig 3. But I wanted to use OP-AMP also in this block. Low pass filter selects only audio signal. The output impedance of OP-AMP is about 1k ohm. Therefore it can not drive a speaker directly. So I use a transformer. But now I think it is better to use a emitter follower indicated on another page. I can hear JOAK(594kHz) and JOAB(693kHz) by tuning the oscillator. This radio has the total gain 4+23+29+4+17=77dB. 1m wire is enough antenna. If I could get a high frequency OP-AMP, I could make MW full band radio.............Add on 5 Dec 2000: I tried to make MW full band radio with faster OP amp, but it is very diffecult!
控え目なπ乙 6600V has been converted into 100V or 200V of the domestic use with the transformer on the pillar as shown in left figure. If the insulation of this transformer is bad, high voltage apears second side of the transformer. So, it is very dangerous. To prevent this, the electric wire on the second side of this transformer is grounded. Because second side of this transformer is grounded, We gets an electric shock when we touch with the case of an electric product that leaked electricity. It is the mechanism that leaks electricity and gets an electric shock with electric product.