Triangle wave generator

[pkplex]

Current circuit, with a 1nF cap it works from around 20Khz to around 400Khz without rounding the triangle waveform. Much fun

Thanks w2aew

[Zero999]

The LM358 makes a rubbish comparator/Schmitt trigger.

If board space is an issue, the 555 timer could be used but note the higher power consumption and the possible need for extra decoupling capacitors, unless a CMOS variant is used.

[Yansi]

Whats the advantage of this circuit using separate current sources and the switchbridge?

Same results (or nearly similar) can be obtained with the learn-book basic two opamp triangle wave circuit, if you just replace the integrator's input resistor with potentiometer: wiper on comp. output  and ends through diodes to the opamp input.  Or if you want to set the rising/falling slopes separately, then two pots and again two diodes. Simple, easy, working too.

But sure, the diode switch bridge and current source/sink is more entertaining for a beginner. The biggest disadvantage being the nonlinear current setpoint by the trimpots in the emitors. And note there's an error in the PDF from W2AEW on page 4: misslabeled outputs.

[Jay_Diddy_B]

Hi,

The original schematic is not too far off.

It will work if a faster op-amp is used. It needs at least 3 MHz of GBW and 10V/us of slew rate. The TL084 etc will work.

I also had to adjust the values, but I ended up with 2.5V p-p at 7.5kHz






Regards,

Jay_Diddy_B

[w2aew]

<snip>
 And note there's an error in the PDF from W2AEW on page 4: misslabeled outputs.

Where's the error in my pdf?

[Yansi]

I apologize, my fault. I have looked again, no problem. Maybe I was too tired and sleepy  when I checked last time.

By the way, you have a great YouTube channel, good source of inspiration. 

[w2aew]

I apologize, my fault. I have looked again, no problem. Maybe I was too tired and sleepy  when I checked last time.

By the way, you have a great YouTube channel, good source of inspiration. 

Thank you.  I do my best to keep errors out of my videos and support materials, but sometimes they do slip by - so I am happy to hear when someone finds a problem so that I can go back an fix it.