Electronic Circuits and Projects Forum

How about the transmitter? I have the schematic but don't have the parts. Can I replace those components?
I think the c9018 is KTC9018, if I want to replace with another transistor, which rating between them should be the same? Is it the frequency? What about the value of rfc?

Thanks

If you change the transistor then the new one will have different capacitance and gain so the frequency and output level will be different. It looks like its frequency is not adjustable.
Try a different RFC, it will probably work.

Yes, the frequency of the transmitter is not adjustable, the adjustment is being done on the receiver. Must the value of the rfc for both transmitter and receiver be consistent? They are the same for the original circuit, if I change for the transmitter, then I need to change for the receiver as well right?

Maybe I should start replacing a part followed by another part.

Thanks

The RFC doesn't affect the tuned frequency. Its inductive reactance is just a high impedance.

Hi,
The schematic of the transmitter comes with the transmitter, but I found that on the schematic, the oscillator is made by NAND gate, but it is a HEF4001BP, a NOR gate. If it is a NOR gate, then should I change to pull one pin down?

Can I use normal logic gate such as 74ls00 or 74ls02 to do oscillation? I've tried with the same circuit, cannot.

Thanks

The output of a NAND gate goes high if an input goes low.
The output of a NOR gate goes low if an input goes high.

The modulating oscillator is for Cmos logic, not old TTL logic.

Then I have to trust the internet that HEF4001BP is a NOR gate but not a NAND gate. I have wasted another PCB which has already been drilled and ready to solder..

A CD4011 or a HEF4011 is a Cmos quad NAND gate package. Its pins have the same layout as a 4001.

Originally Posted by audioguru

A CD4011 or a HEF4011 is a Cmos quad NAND gate package. Its pins have the same layout as a 4001.

Oh, then I can remain to use the design for NAND gate, thanks.

This is the receiver circuit that I've just done. The IC is LM567/NE567 phase lock loop.

This receiver circuit is designed for 12 volts, but I plan to use only 9 volts then I have to change to 9v relay. How about the zener diode?
From the schematic, I think when the signal is received, pin 8 of the phase lock loop gives a low, to turn the LED on and also the relay. If I don't want to use a relay, then I replace it with a resistor, and pin 8 to the microcontroller, can I?
I know the coil paralleled with the trimmer cap is to oscillate at 300MHz, but what's the purpose of the coil and the resistor at the antenna side? From the board, these coils are located near to each other.

Thanks