gres
Full Member level 4
Amplifier is 2x25W with AUX and phonograph input. I needed it cause my father consist large library of vinyls, and phonograph. Audio system that phonograph used to was plugged have missed somewhere. Audio system that I use now don’t have phonograph input. Of course solution was to buy photographer preamplifier, but I decided to make it by my hands, both: preamplifier and amplifier.
Assumptions:
- device should work with phonograph
- work with other devices
- headphones
- middle power ( I didn’t won’t to have stun machine)
realization:
I found a lot projects at the internet. Also there was some ready kits. I decided to split project to a few parts that are placed on other boards:
1. preamplifier
2 input selector, overtune indicator ( additional trick), and amplifier
3. headphones amplifier
4. power
phonograph preamplifier:
the best I found is AVT1023 kit “ phonograph preamplifier with RIAA characteristic”. I made some changes in elements and printed board.
Input selector:
Two stereophonic inputs ( AUX and phonograph) should be plugged to amplifier. To choose one of the devices I used double analogue multiplexer – 4052 system. It consist 2 bits address at my project one of the bits is constants plug to the ground, second is also plug to the ground but via 100k resistor and to vcc via switch.
Overtune indicator:
It’s a trick element. It based on 2x5 LED ( 4 green and 1 red) and for steering is KA2281 system.
Amplifier:
Main amplifier is TDA7265.
Headphones amplifier – TDA7050
Power: for amplifiers +/-24V . Rest elements +/-5V Stabilizers powered by transformer 100W 230/2x24V
More information athttps://www.elektroda.pl/rtvforum/topic1611078.html