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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets.

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Old 2nd Aug 2017, 4:47 pm   #61
Herald1360
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Default Re: First Radio Build - 12V HT system

6 (+ve) looks OK. 5 (output) looks bad, should be around half rail. Has the capacitor between it and the speaker been missed out? Connecting direct through speaker to ground could explain.
7 (Bypass) is plausible.


http://www.ti.com/lit/ds/symlink/lm386.pdf
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Old 2nd Aug 2017, 5:43 pm   #62
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Default Re: First Radio Build - 12V HT system

I just checked and it's definitely connected to the 100uf electrolytic. It still reads at 0.60V.

Cameron
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Old 2nd Aug 2017, 7:54 pm   #63
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Default Re: First Radio Build - 12V HT system

Hmm, circuit of LM286 stage? Is the biassing right?

Could just be knackered chip.
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Old 2nd Aug 2017, 8:32 pm   #64
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Default Re: First Radio Build - 12V HT system

So should I just do a final check if my wiring then if nothing is wrong buy a new chip? Or is there anything else I can measure first.
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Old 3rd Aug 2017, 11:44 am   #65
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Default Re: First Radio Build - 12V HT system

A careful measure of every voltage on the LM386 pins might help.


A circuit showing us how you think it's connected up would be useful. The TI link I posted yesterday shows one way it could be connected up and work OK.
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Old 3rd Aug 2017, 4:02 pm   #66
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Default Re: First Radio Build - 12V HT system

Hi All,
This is the circuit I use for radio circuits. It keeps the rf well away from the amplifier.
Paul.
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Old 3rd Aug 2017, 7:07 pm   #67
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Default Re: First Radio Build - 12V HT system

Quote:
Originally Posted by Herald1360 View Post
A circuit showing us how you think it's connected up would be useful. The TI link I posted yesterday shows one way it could be connected up and work OK.
It's connected up following the pin numbers on the document you send and using the circuit diagram I attached a few pages back. I will measure the voltages tommorow. It's probably something stupid but I'm new to building circuits rather than just repairing things following a guide. I have built a few things but this is the most complex. I really hope I can get it working. Thanks for your help,

Cameron
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Old 3rd Aug 2017, 7:09 pm   #68
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Default Re: First Radio Build - 12V HT system

Quote:
Originally Posted by kalee99 View Post
This is the circuit I use for radio circuits. It keeps the rf well away from the amplifier.
I'll keep that in mind for if I can't get this one working, it does look fairly similar to the one I'm using. Thanks for your help,

Cameron
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Old 5th Aug 2017, 5:10 pm   #69
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Default Re: First Radio Build - 12V HT system

I got the voltages measured today with my new fluke 25
Here are the results:

Pin 1-1.28V
Pin 2-0V
Pin 3-0.053V
Pin 4-0V
Pin 5-0.60V
Pin 6-12.18V
Pin 7-6.37V
Pin 8-1.63V

I have attached another copy of the circuit diagram I used. Thanks for the help,

Cameron
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