Author Topic: Basic inline preamp diagram required.  (Read 1134 times)

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Offline drummerdimitriTopic starter

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Basic inline preamp diagram required.
« on: April 26, 2019, 03:55:19 pm »
I watch movies on a projector but the 3.5 mm output signal is too low so even when I turn the volume to the max on my sound system, the loudness is not satisfactory.

Would like to assemble a basic preamp to double the output voltage of the signal. Does anyone have a circuit diagram I can use to assemble this device?
 

Offline Tek Tech

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Re: Basic inline preamp diagram required.
« Reply #1 on: April 26, 2019, 04:34:23 pm »
A simple one-transistor amp should work. One for each channel.
They can be cascaded if you need greater amplification.

[Edited from emitter follower. Thanks to Benta's observation one post below]
« Last Edit: April 27, 2019, 05:14:54 am by Tek Tech »
 

Offline Benta

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Re: Basic inline preamp diagram required.
« Reply #2 on: April 26, 2019, 05:33:05 pm »
A simple emitter follower should work. One for each channel.
They can be cascaded if you need greater amplification.



Just a little problem: emitter followers have a voltage gain of less than 1. Not the right solution.
 
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Online moffy

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Re: Basic inline preamp diagram required.
« Reply #3 on: April 27, 2019, 12:07:43 am »
Attached is a possible solution. Use an LM833 dual, you get 2 opamps therefore stereo. Has a gain of 2.2 but you need a +/-12v supply as well.
Caps should be non polar (not electrolytics) and avoid ceramics for the 1u.
« Last Edit: April 27, 2019, 12:09:50 am by moffy »
 
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Online MarkF

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Re: Basic inline preamp diagram required.
« Reply #4 on: April 27, 2019, 03:12:51 am »
Here is a pre-amp for a condenser mic.  Maybe you can tweak the gain for your case.

   
 


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