Hi all,
I mentioned in DRkilljoy's function generator post 'here', that I had just breadboarded an Icl8038 based function generator. Well I had and it was based on 'this' circuit.
It worked quite well, There was some distortion of the various wave forms, but that may well have been due to the fact that I didn't have much in the way of decoupling, and also that it was on a breadboard.
So anyway the ICL8038 is able to provide a sweep function, but that circuit didn't use this in it's design. I understand that a sweep function is useful, and I wanted it, so I started to google for a circuit that did provide this function.... Noooo joy.
But I did find 'THIS' circuit, when I looked at it closely, I realised, that it was a much more sophisticated design. I liked the way that it filtered out the DC offset, amplified the signals to a standard level and provides a switching range. All in all, a much more proffessional design, rather than the almost reference datasheet design from the other website, but still no sweep function! So without having found a circuit that provides the said sweep function, I have to take it upon myself to do it!!!
I've built the circuit on my breadboard and it works really well (some pictures below), I've had to substitute some cap's until I can get some of the correct tolerance but all is near enough as it should be.
I expect to receive my polystyrene caps in a day or two, so meanwhile. I'd like to discuss the sweep function issue.
From the datasheet (page 6) :-
I take it that the signal that I need to apply at pin 8 is a ramp of some sort! If that's correct could I possibly use a dual op-amp instead of a single for IC5, providing a saw tooth by way of a switch in order to achieve a sweep function? I'm going to try this anyway....
Also I was thinking I could possibly add in a small PIC (with an ADC) to provide an LED output, maybe even switch that, so as to give a frequency counter as well.
I'm going to take this one step at a time though, so far I have a working basic design, I'm going to transfer this to matrix board, to see if I can do that successfully... then add in the extra features one by one.
What do you think? (I know about the Pic based gen's that are available)
I mentioned in DRkilljoy's function generator post 'here', that I had just breadboarded an Icl8038 based function generator. Well I had and it was based on 'this' circuit.
It worked quite well, There was some distortion of the various wave forms, but that may well have been due to the fact that I didn't have much in the way of decoupling, and also that it was on a breadboard.
So anyway the ICL8038 is able to provide a sweep function, but that circuit didn't use this in it's design. I understand that a sweep function is useful, and I wanted it, so I started to google for a circuit that did provide this function.... Noooo joy.
But I did find 'THIS' circuit, when I looked at it closely, I realised, that it was a much more sophisticated design. I liked the way that it filtered out the DC offset, amplified the signals to a standard level and provides a switching range. All in all, a much more proffessional design, rather than the almost reference datasheet design from the other website, but still no sweep function! So without having found a circuit that provides the said sweep function, I have to take it upon myself to do it!!!
I've built the circuit on my breadboard and it works really well (some pictures below), I've had to substitute some cap's until I can get some of the correct tolerance but all is near enough as it should be.
I expect to receive my polystyrene caps in a day or two, so meanwhile. I'd like to discuss the sweep function issue.
From the datasheet (page 6) :-
For larger FM deviations or for frequency sweeping, the
modulating signal is applied between the positive supply
voltage and pin 8 (Figure 5B)
I take it that the signal that I need to apply at pin 8 is a ramp of some sort! If that's correct could I possibly use a dual op-amp instead of a single for IC5, providing a saw tooth by way of a switch in order to achieve a sweep function? I'm going to try this anyway....
Also I was thinking I could possibly add in a small PIC (with an ADC) to provide an LED output, maybe even switch that, so as to give a frequency counter as well.
I'm going to take this one step at a time though, so far I have a working basic design, I'm going to transfer this to matrix board, to see if I can do that successfully... then add in the extra features one by one.
What do you think? (I know about the Pic based gen's that are available)
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