| Electronics > Projects, Designs, and Technical Stuff |
| Simple but Fully Discrete Triangle Wave Generator |
| (1/1) |
| PinePolarBear:
Hello. I'm working on a fully discrete class D amplifier. I'm looking for a triangle wave generator design. It would be preferably simple, but it needs to go above 250 kHz. Thanks. |
| JPortici:
Component selection and how to get around all the gotchas to achieve an triangle that as pure and symmetric as possible is left as an excercise to the reader |
| Benta:
You should add that the triangular output is from the first amp. |
| T3sl4co1l:
I've used some variant of this, many times: https://www.seventransistorlabs.com/Images/Flashlight2_Schematic.png IC2 is a astable multivibrator and PWM comparator. Q4A isn't necessary, but it improves linearity. If not needed, it can be replaced with a pull-up resistor. Note that you don't want to skip the rest of the circuit: IC3B compares the inductor current to the current setpoint, providing a first line of defense against destruction of transistors or other components. The output current simply cannot be anything other than what it can be set to, within a controlled range. IC3A then controls that current, in order to regulate the output value (in this case, a combination of output current and voltage for driving LEDs, but just voltage would be fine for a power supply or amplifier). The chained error amplifier topology also avoids putting the double-pole output filter inside a single loop. Instead, the inductor is in the first loop, and the capacitor and load in the second. This is much easier to compensate, and gives much nicer waveforms. Tim |
| David Hess:
Oscilloscope sweep generators meet your requirements so you might want to study how they work. I would also consider bipolar implementation of a PUT based relaxation oscillator with the resistance replaced with a constant current source. https://www.instructables.com/id/Circuit-Collection-of-the-Programmable-Unijunction/ |
| Navigation |
| Message Index |