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c3 must be <100 pf F=18khz
c4 must be 5 pF or 10 pf
Can't you measure those?
Conventional C-meters allows in-circuit measurements (at least the one i have).
C3 can be <100pF.
C4 can be even omitted or in range <470p i suppose.
@N@SKO :
Nice work !
But only OP1 supply is shown.
What about others OP AMP ?
A 78L08 regulator is used for +8V and a Ucc384 regulator for -5V.
What do you think about LM2930T-8.0 together with a 79L05 ?
You don't need a LDO regulator for -5V.
The 79L09 dropout voltage is 1.7V and you get -8V from the 7660 : |-8V| - 1.7 = 6.3 V which is higher than |-5V|.
(Just like the +5V line).
In the other hand, you can use LDO regulators for both +5V and -5V.
Moreover, with the LM2930T-8.0, you can power the card with a single 9V battery.
The audio stage can works with 9V.
Note : if you want a standalone operation of the voltage inverter, you can used a MAX1044 instead. It's got a boost pin to increase the internal oscillator above 30Khz. http://datasheets.maxim-ic.com/en/ds...60-MAX1044.pdf
1) Who can explain these switches ?
What are they doing ?
I don't understand the relationship with the 4053 IC ... They are drawn like mecanical switches.
1) Who can explain these switches ?
What are they doing ?
I don't understand the relationship with the 4053 IC ... They are drawn like mecanical switches.
2) Is this a pot. or a trimmer ? What for ?
Thank you,
Hugo
I think the switches are not needed.
P 101 - trimmer
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