Can I use BD135 or 136 (NPN) instead of old SL100 here?

[audioguru]

Many products do not work properly when powered by a square wave.
The transistors increased the square wave current to quickly charge and discharge the high input capacitance of the Mosfets.
One IRFZ44 Mosfet can conduct 36A when it has a pretty big heatsink which is a power of 36A x 12V= 432W. Then one pair of them alternate the 432W with a pause when the other Mosfet is conducting so the output power from one pair of these Mosfets driven by the complementary emitter-follower transistors can be 864W.

 

[Willen]

Hi,

In the 4047 chip, many circuits I found 47k and 0.1uF capacitor (at pin 1, 2, 3) to produce 50Hz output. Today I got a 10nF and 390k paralled with 100k POT to get variable frequency.

Is there any relationship in output power vs frequency? Do I get high power out with higher frequency than lower?

 

[audioguru]

Texas Instruments says on their datasheet that the timing resistor for the oscillator in a CD4047 circuit must be between 10k and 1M. Yours is fine.
The output power is calculated with voltage times current. Some transformers perform poorly at very low or high frequencies. That is one reason that modern audio amplifiers do not use transformers.

 

[Willen]

SW and MW radio has less frequency and has less quality too. FM has higher frequency and has good quality. Satellite TV has GHz of frequency and has HD quality. So generally I guessed that the higher the frequency is the higher the output.

Maybe with lower frequency around mains frequency, bulk linear transformers (Iron core) is suitable. I found some small ferrite as output transformer too, maybe that set higher frequency for the high speed transformer to get equal (or more) power than bulky slower (linear) one.

 

[audioguru]

MW AM radio and SW which also has AM modulation use narrow bandwidth that might be less than an old telephone, maybe because it was designed such a long time ago that they did not know how and could not afford the high cost to make it sound better. FM radio has higher quality than MW AM radio or SW not because the radio frequency is very high, but because it has a wide bandwidth from 50Hz to 50kHz almost the same bandwidth as our hearing that is 20Hz to 20kHz.

The "A" in AM stands for Amplitude so the carrier frequency is modulated with amplitude changes but interference like from lightning or other static is also has amplitude changes which is produced as interference sounds on AM radios.
The "F" in FM stands for Frequency so the carrier frequency is modulated withfrequency changes and is not affected by amplitude interference. Then an FM radio produces very little noise and interference.

A big heavy iron core transformer is used for medium low frequencies. A small lightweight ferrite core transformer is used at high frequencies. They "transform" power, they do not make and do not increase power. If they have their designed frequency then their output power is almost the same as their input power.

An incandescent light bulb or an electric heater (same things) produce the same output from 230VAC RMS or from a squarewave with a peak voltage of 230V. But the peak voltage of the sinewave from the mains electricity is 1.414 times higher than its RMS voltage. Many electronic products rely on the higher peak voltage of the sinewave then rectify and filter it to power the circuits. Then a rectified and filtered squarewave produces a voltage that is too low.