Low frequency in this VCO design

Electrical Engineering Asked by somerandomusername on October 5, 2020

I am following this VCO design I found from a tutorial and for some reason the frequency is way too low. It doesn’t state in the design what it should be, but following these instructions it is just couple of Hz. I replaced C1 with 0.01u capacitor and now it is better (30-370Hz), but still that doesn’t seem correct. I tried messing around with some of the resistance values, but only managed to change the duty cycles. Is it a problem with the design or am I doing something wrong?

enter image description here

Updated version of my schematic:

enter image description here

One Answer

You built it well and measured the frequencies accurately. The value of C1 was originally probably 1nF. The signal is a bit asymmetric because the 57k resistors were originally probably 51k. 57k is not a standard value.



I suggest adding 4 more resistors to make the amplitude of the rectangle and the triangle the same.


With C1=1nF, the frequency can be set in the range of 200Hz ... 5kHz.


Correct answer by csabahu on October 5, 2020

Add your own answers!

Related Questions

Preventing long-press button function on DFPlayer board

1  Asked on December 19, 2020 by michael-reilly


Half-wave rectifier with resistor and inductor load

2  Asked on December 18, 2020 by edwin-vargas


Sprintf() function bricked Arduino Nano?

2  Asked on December 18, 2020 by dragos-spiridon


Regarding plugging operations

1  Asked on December 18, 2020 by kamola


Debugging Signal Distortion/Oscillation

1  Asked on December 18, 2020 by cdevelop


Can a MOSFET work upside-down?

2  Asked on December 16, 2020 by user253751


Am I using this LM393A comparator incorrectly?

2  Asked on December 15, 2020 by ttbulaski


Bonding yourself via oscilloscope GND?

1  Asked on December 14, 2020 by manuel


Would a ground plane/traces impact NFC antenna performance?

1  Asked on December 14, 2020 by yonatan-avhar


Thermal compound for Alumina Ceramic Insulator

2  Asked on December 14, 2020 by uk25


Ask a Question

Get help from others!

© 2023 All rights reserved. Sites we Love: PCI Database, UKBizDB, Menu Kuliner, Sharing RPP