5 Transistors Linear Triangle Wave Generator

crutschow

Joined Mar 14, 2008
25,446
An interesting circuit.
But it appears to depend upon careful selection of some of the parts, including transistor gain, to get a symmetrical triangle wave.
Building the actual circuit may require tweaking of the values to get the desired waveform.
 

Thread Starter

iimagine

Joined Dec 20, 2010
482
I guess there is no way to have fixed gain. I could have the charging transistor to a fixed gain of 10 but theres no way it can be done for the discharging transistor.
Well....here's a simple and cheap solution: Diodes!

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Thread Starter

iimagine

Joined Dec 20, 2010
482
So, I finally decided to bread board this thing just to see how linear it gets. Got it all hooked up all and everything. Plugin my Hantek 6022BE USB oscilloscope and got a 'USB Device descriptor failed' error! :confused: Spent like a couple hours plugin it in and out but no luck :(. Search the net for solutions but none worked. I got mad and plugin an LED at the output, use a 1000uF cap and stare at the fading in out light. I guess I'll never know till i can get another scope
 

Thread Starter

iimagine

Joined Dec 20, 2010
482
Well Arduino oscilloscope turns out not to bad for low freq :)
The waveform was as I expected, falling edge is not so linear because i didnt have a larger then 680k base resistor
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danadak

Joined Mar 10, 2018
4,057
If you do not have a scope here is a low speed freebee -

You can start with a PC sound card based scope for free. Will give you basically
audio range scope, spectrum analyzer, and function generator all using your
PC sound card. It may not be fast enough to handle the character LCD interface
however.


https://www.zeitnitz.eu/scope_en

But first build a simple circuit to protect sound card inputs so you do not
ruin from transients, overvoltage. Google "protect sound card input".

For example http://makezine.com/projects/sound-card-oscilloscope/


http://www.zelscope.com/


http://www.ledametrix.com/oscope/


http://www.virtins.com/downloads.shtml


Use 10x probe, DIY 10x probe - https://cromwell-intl.com/radio/probes.html


A real inexpensive Logic Analyzer/pc combo can be had with this -

https://www.ebay.com/itm/USB-Logic-...h=item33f2ef28ec:g:NNoAAOSwjXVaoiyH:rk:4:pf:0

There are many vendors of this on ebay.

You download and install Saleae software to run it. https://www.saleae.com/downloads/

Sound card impedance bridge -

http://www.marucchi.it/ZRLC_web/ZRLC/Steber_An_LMS_Impedance_Bridge.pdf


http://www.sillanumsoft.org/ZRLC.htm


Regards, Dana.
 
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