NE566 Clamping

[glenlivet]

Howdy,
I'm putzing around with an NE566. I've noticed on a single polarity power supply that the square and triangle wave outputs float about .4 volts above ground (0v) and are not
full rail to rail (0 to +12v) amplitude. I am converting the triangle to a sine wave with the standard circuit that uses diodes and a 741 op amp. I need some suggestions on clamping the bottom of the square to ground and restoring the amplitude to 0 to +12volts and clipping off the bottom of the sine wave wave to 1/2 cycle so that the 180 degree phase of the sine wave is also 0 to +12 volts. I'd like to empl0y the KISS concept and keep the parts count to minimum.

Thanks in advance

 

[crutschow]

Show your schematic.
The 556 does not have rail-rail outputs but the low level should be close to ground unless you have a significant output load resistance connected to the V+.

 

[audioguru]

The NE556 was introduced many years ago. Its internal circuit is similar to old TTL logic.
A TLC556 uses more modern Cmos technology and its output is rail to rail when the load resistance is fairly high.

The very old 741 opamp has inputs that do not work anywhere near ground.

 

[k7elp60]

You need post your circuit for the 566 IC. If I read the data sheet correctly you need both + and - volts on the IC.

 

[audioguru]

Oh. An NE566 function generator?
Its datasheet shows it with +12V and does not say if it has 0V or a negative supply. Its triangle output voltage on a graph going from about +3.6V to about +6.0V(2.4Vp-p).
A 741 is a useless very old opamp. Use a modern rail-to-rail opamp as a level-shifter and amplifier.

 

[glenlivet]

I'm using the 566 as the base in a design because it is easily implemented and maintains a reasonable 50% duty cycle
across the frequency span which the 555 does not. Plus I need an easily obtainable sine wave to frequency modulate another 566 VCO.
I just wanted to keep it simple and hopefully not have to use dual polarity power supplies.
One may ask why I would want to implement the 556 in a new design? While the NE566 is an obsolete part there are still thousands available for relatively cheap
in quantity from the trailing edge technology chip marketers. More than I will ever use in a limited production device.
I've posted the circuit I'm using at **broken link removed**