Hi guys/gals...
Well after destroying the first version, (see existing photos in the AudioScope thread), I have come up with a fully isolated version.
It has _unity_ gain, flat from 300Hz to at least 30KHz and about 6dB down at 100Hz.
I have absolutely no idea as to the audio passband of the Mic input of this Macbook Pro 13" but it seems to be flat and very sensitive.
I have worked out a calibration technique that requires only the circuits so far plus the Arduino for any DC stuff...
I have decided to show you all the Y amp circuit before I put it into the script.
Photos will be done shortly and I await the flak... ;oD
Enjoy...
Code
# #########################################################
# The FIFTH extremely simple circuit diagram.
# Completely Isolated Vertical Amplifier.
# +----------------o-----------------------------o----o------+
# | + | | | |
# C1 === | |LED1| + |
# --- c o Preset. \ --+-- |
# __|__ \ b R3 RV3 / / \ >>> |
# ///// Q1 \|__o---o----/\/\/\----o---|\ '---' |
# Secondary. Primary. /| | | / | |
# Tip -----> O +------+ R2 |/_ | I/P C4 | + \ \ |
# Ring 1 --> H | | T1 +---o--/\/\/\--o e C3 --- +--O)-+ === / / |
# Ring 2 --> H <--+ | | | | --- | SK1 | --- | R4 \ ZD1 | +
# _Gnd_ ---> H <--+ )||( | C2 | | \ | | | / --+--+
# +===+ | )||( +---| H----o | / | | | \ / \ |
# | | | )||( + | | \ +----o----o / '---'
# P1 | | | (CT) o)||( | RV1 +-->/ | | |
# | | | )||( | Variable. \ | o |
# \ / | )||( TP1 O / | S1 / |
# H | )||( | | o |
# Tip. ~~~ | | | | | + | |
# ^ | | | \ | __|__ |
# | Ring 1. | \ | Preset. / | === |
# | ^ | / | RV2 +--|\ | | |
# | | R5 | R1 \ | | / | BY1| |
# | +--/\/\/\--o / | | \ | __|__ |
# | | \ | | / | === |
# | | / | | | | - | |
# | R6 | | | | | | | |
# +-----/\/\/\-----o------+ G O------------------------o---o---------------o----o------+
# __|__ Diecast box GROUND.
# Parts List:- /////
# P1 ......... 3.5mm, 4 pole jack plug.
# T1 ......... Audio Transformer, P/No Farnell 1172421.
# [OEP (OXFORD ELECTRICAL PRODUCTS) - Z1604 - TRANSFORMER, 1:1, 600/600].
# R1 ......... 2K7, 1/8W, 5% tolerence resistor.
# R2 ......... 680R, 1/8W, 5% tolerence resistor.
# R3 ......... 47K, 1/8W, 5% tolerence resistor.
# R4 ......... 330R, 1/8W, 5% tolerence resistor.
# R5, R6 ..... 33R, 1/8W, 5% tolerence resistor.
# RV1 ........ !M Log, potentiometer.
# RV2 ........ 1K, preset potentiometer.
# RV3 ........ 100K, 10 turn, preset potentiometer.
# C1, C4 ..... 10uF, electrolytic, 16V.
# C2 ......... 3300uF, electrolytic, 6.3V.
# C3 ......... 2.2uF, 50V.
# Q1 ......... BC548B, or any small signal silicon NPN transistor.
# SK1 ........ BNC chassis mounted socket.
# S1 ......... ON/OFF toggle switch.
# LED1 ....... Miniature GREEN LED.
# ZD1 ........ 5.1V Zener diode.
# BY1 ........ PP3 battery.
# PP3 battery connector.
# Diecast box.
# Link terminals, as required.
# Stripboard, (Verobaord), as required.
# Various coloured and tinned copper wire as required.
# Heat shrink sleeving as required.
# Small cable ties, optional.
# Stick on cable clip, optional.
# Crimp ring terminal, for connection to point G.
# Srews, washers, spacers, nuts, grommets, etc as required.
# #########################################################
