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Homebrew Equipment A place to show, design and discuss the weird and wonderful electronic creations from the hands of individual members. |
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4th Feb 2024, 2:28 pm | #1 |
Hexode
Join Date: Dec 2018
Location: Lugo, Spain
Posts: 483
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Simple transistor electronic keyer for qrp help
Built it then re-built it , checked all components and connections , changed transistors but to no avail, the only things i do not have are the 3.3 uf caps so i,m using 10uf would this really make a difference , its just not working .
It seems like a good circuit adapted from an astable multivibrator . Does anyone have any clues why this would not work?. See the third circuit down from top of page. https://www.abcelectronique.com/annu...r-astable.html |
4th Feb 2024, 3:52 pm | #2 |
Moderator
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,918
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Re: Simple transistor electronic keyer for qrp help
The wrong capacitor values will reduce the keying speed by a factor of three.
If one or both of the capacitors is leaky, operation is going to be prevented. The astable multivibrator like that has a bug. Depending on the gain of each transistor, there is a possibility of both transistors turning on at once. Some voltage measurements are needed to get any chance of seeing what's going on. It's a good candidate for one of the newer digital storage scopes. A good example of the very simple circuit if you count components, but which can be very difficult to get going. David
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4th Feb 2024, 6:35 pm | #3 |
Hexode
Join Date: Dec 2018
Location: Lugo, Spain
Posts: 483
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Re: Simple transistor electronic keyer for qrp help
Thank you, i will see if smaller caps do the trick first, looks like a search in the junk box.
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