Now I will tell you how to do a push-button dual volume control only on a single chip. There's this Korean firm Samsung. This office produces unremarkable domestic crafts such as mobile phones and tanks. But they can dig up something nice. This time is a microchip CA. The chip is an electronic volume control with the following settings:

The control range, dB 0...66
The adjustment step, 2 dB
The working frequency band, Hz 20 20000...
Harmonic distortion, % 0,005
The voltage, V 3 16...

Shemka like this:

Electronic volume control on KA2250

No, no, no need to be frightened - I said - Koreans. They seem to have their own, specific idea about the convenience of the location of the pins and the topology of the circuit. Anyway - the main thing is not too many wall elements, so the chance to get confused still decreases. Actually, to describe there is a signal on the appropriate conclusions, all regulated by two buttons S1 and S2.

As our brothers in mind not provided in the chip non-volatile memory, one would conclude that the volume will need each time to re-set each time you turn the scheme. But no - they got out of this situation in his own way, in Korean. At power-charging the capacitor C9. Once power is lost and the pin 7 of the chip leaves the level of the log. 1, the chip immediately closes all of its inputs and outputs and switches to the mode of consumption of nanotool. Thus, she takes them of course from the capacitor C9. I'll be honest - how long this system will be able to keep it all in working condition, I don't know. Maybe it's just protection against short interruptions in power supply.

A table with a list of items:

The symbol on the diagram

The value

C1

a 4.7 µf

C2

a 4.7 µf

C3

a 4.7 µf

C5

a 4.7 µf

C6

a 4.7 µf

C7

a 4.7 µf

C4

MF

C8

a 4.7 µf

C9

Thu

 

 

R1

10k

R2

22kohm

R4

22kohm

R5

Am

R6

100k

R3

Am

R7

10k

 

 

S1

Any push-button momentary

S2

Any push-button momentary

 

 

VD1

CD

VD2

CD

VD3

KD 503

Chip

CA

 

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