helps needed

[chinsoon]

by the way, i heard a some people saying that for RF circuits, its not so suitable to test it on bread board. it will cause error. just want to seek for opinions of all of you here about this. is that true?

 

[Nigel Goodwin]

by the way, i heard a some people saying that for RF circuits, its not so suitable to test it on bread board. it will cause error. just want to seek for opinions of all of you here about this. is that true?

Yes, breadboards are not suitable for RF, and are barely suitable for audio frequencies!.

 

[chinsoon]

Yes, breadboards are not suitable for RF, and are barely suitable for audio frequencies!.

so whats the reason behind it? with breadboard, RF circuit definitely will not work is it?

so i have to constuct them on a PCB instead?

 

[gramo]

It’s the capacitance that the traces create along the tracks on a breadboard. Think of each track as a capacitor, with 2 sheets of metal and air as the dielectric

 

[chinsoon]

It’s the capacitance that the traces create along the tracks on a breadboard. Think of each track as a capacitor, with 2 sheets of metal and air as the dielectric

i see. oh no.. thats bad news...

so lets say even if now for my second circuit, i have the PCB board (actual one) and i want to redraw it, can i just draw it using free hand, without using any software?

and today when drawing the PCB board, i sort of like run out of space to draw one of those lines. can i just use a jumper to connect them? or it will affect my output as well?

 

[Nigel Goodwin]

so whats the reason behind it? with breadboard, RF circuit definitely will not work is it?

It's the extra capacitance between the different tracks, depending on the exact layout, and at only low RF frequencies, it 'may' work - but the chances are against it, and it's a waste of time trying.

so i have to constuct them on a PCB instead?

Or stripboard?, but again you need to be careful with the layout, and remove unused tracks and parts of tracks. The same applies to a PCB as well, you need to consider the layout if you expect it to work, and the higher the frequency the more critical it is.

 

[chinsoon]

Or stripboard?, but again you need to be careful with the layout, and remove unused tracks and parts of tracks. The same applies to a PCB as well, you need to consider the layout if you expect it to work, and the higher the frequency the more critical it is.

ok...thats something new... actually this is the first time i am involve in this kind of project..

so i've done google.... and it seems like what you suggest, a stripboard is quite easy to use... so it works for RF 27MHz is it? so i think i will redo my first circuit again.

and nigel, you've seen my first circuit right? in the very beginning of this thread? theoretically it should work (like what you mentioned last time in this thread as well), but is there any possibility that the values given are wrong and the circuit will not work. i mean from theory side, i think it should work. but practically, will it?

 

[chinsoon]

It’s the capacitance that the traces create along the tracks on a breadboard. Think of each track as a capacitor, with 2 sheets of metal and air as the dielectric

i see. oh no.. thats bad news...

so lets say even if now for my second circuit, i have the PCB board (actual one) and i want to redraw it, can i just draw it using free hand, without using any software?

and today when drawing the PCB board, i sort of like run out of space to draw one of those lines. can i just use a jumper to connect them? or it will affect my output as well?

 

[Nigel Goodwin]

ok...thats something new... actually this is the first time i am involve in this kind of project..

so i've done google.... and it seems like what you suggest, a stripboard is quite easy to use... so it works for RF 27MHz is it? so i think i will redo my first circuit again.

It'll work if designed correctly - Audioguru even got a VHF transmitter working on stripboard!.

and nigel, you've seen my first circuit right? in the very beginning of this thread? theoretically it should work (like what you mentioned last time in this thread as well), but is there any possibility that the values given are wrong and the circuit will not work. i mean from theory side, i think it should work. but practically, will it?

Looks OK to me, a simple superhet - don't forget to connect the IF transformer the correct way round this time!, and did you replace your ZN414?, it may well have been killed by the incorrectly connected transformer.