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Electronics -- Small Footprint Square Wave Oscillator

Oscillator

As already pointed out on the parent page, this is a small footprint 50% duty cycle square wave oscillator with variable frequency from 10kHz to 30MHz. The frequency range can be extended to 1kHz by using 1M instead of 100k for R6.
Supply voltage is 5V (5.5V max); lower voltages (e.g. 3.3V) can also be used but will limit the maximum frequency to values significantly below 30MHz.
The sheet presented here drives the square wave directly into 50 Ohm; the output stage uses 5 parallel 74AC04 CMOS inverters which sums up to a total of 120mA max. (Some people may shout at me here because I did not use parallelizing resistors between the gate outputs. Oh well, but it works fine for me this way...)

Circuit

Download oscillator circuit schematic:
PNG image (715x524 as seen below): ltc1799-sheet.png (9kb)
High-quality PDF: ltc1799-sheet.pdf (49kb)
Permission to copy and use this schematic is hereby granted provided credit is given where it is due.

oscillator circuit schematic [9kb]

Prototype

Oscillator prototype photo [5kb]
[click to enlarge: 40kb]

The image on the left shows the prototype of the design. Some people may say that this is not "small footprint". But then please note that the actual oscillator is just R5, C4 and IC1 which can be seen in the magnification circle on the right top. Everything else is for frequency selection (R6, S1) and the output stage (C5, IC2 and the large BNC connector).


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Last modified: 2006-02-28 01:34:28