I want to make a 455khz tunable bfo without any transformers based on the model on this page.
Ceramic resonator bfo circuit.
This i found easier that trying to set it up with the frequency meter.
3 used transistor bc548 9 volt supply voltage rf signal is produced with 455 khz ceramic crystal.
Ceramic resonators ceralock lead type two terminal csbla series.
A ceramic resonator will not allow you to move the frequency more than a little.
Oscillation is near 455 khz stable within a few hz.
Perhaps they ll inspire me to build one hhny2all.
The filter s center terminal normally grounded is connected to the current limiting resistor.
I taped a short length of wire from the output across the back of the circuit board and then adjusted the slug to give me the correct note.
Inverters u1d e along with ceramic resonator x1 form a stable 0 5 455 khz oscillator.
It s not perfect but definitely helps tune the if coils in the elenco am kit.
Crystal oscillator vs resonator.
The following circuit uses a 455 khz ceramic resonator which gives good frequency.
Turn the receiver off and then on at any time and temperature the bfo frequency is exactly the same.
I built this because at the time i didn t have a signal generator that would perform am modulation.
I will try to get some photographs off to hans in the next day or so but life has been hectic over this weekend.
In conclusion has anyone any photos of a mini sized bfo circuit built with a ceramic resonator.
All about circuits.
This circuit was used to stop all the bfo drift.
The input and output of the ceramic filter are tied together.
Nand gate u2a is the modulator and provides a 100 square wave modulated signal.
Nand gate u2b buffers the original unmodulated signal and its propagation delay ensures that its output is in phase with the output of u2a.
Discussion in general electronics discussion started by richard9025 feb 5.
The last time i checked i didn t find it on the site but.
455 khz tunable bfo circuit reply to thread.
The objectives of if alignment are to ensure that all tuned circuits in the if stages are tuned to the same frequency and that this frequency is the correct frequency usually 455khz.
Just curious for input at this point i m not an egineer so i can t directly contribute to our community with such a pico sized hack.
The circuit is extremely stable.
