R7
22R
C6
10
C1
0 47
R1
900k
100:1 divider
C5
4n7
1
DL6GL, 08.03.2018
2
R5
47k 1W
7
Analogue AC Millivoltmeter 10Hz...500kHz (±1%)
+12V
D2a
BAV199
P1, 25k
multi turn
7
3
3
+
2
-
1
IC1
LF356
5
R3
-12V
6k81
4
22R
3mV
R8
3mV / 0.3V
R9
2
1
+
71mV
8
6
-
IC2
OP37
4
3
3k3
+
IC3
OP37
7
+
D3
D4
D5
D6
10 A
78mV FS
Ri 7.8k
6
R20
2
-
4
C15
4 7
D7
R10
215R
C10
1.8...2.2p
(Frequency comp.
R12
68R1
47k
R17
33R
R11
D3...D6: Ge-Diodes,
e.g. 1N34A, AA143
D7: Si diode, e.g. 1N4148
C14
0 1
100R
1000mV / 100V
Closed:
Range x 100
C13
47
680R
14
C9
0 1
300mV / 30V
-12V
R23
R21
Adaption to different analogue meters with
R21 and P3: see Excel sheet
5k6
6
681R
2
+12V
Reed relay
DIP9051-L
12V
13
R13
6
9
7
8
Shaded resistors:
Metal film 1% or better
-12V
+12V
R16
R14
12V
78L12
Reichelt Metallschicht 1%, TK 50ppm/°C
6.810,00
1
2.150,00 0,31596081
-0,08%
681,00 0,10000131
0,00%
215,00 0,03159739
-0,08%
68,10 0,01000144
0,01%
31,47 0,00316104
-0,04% =33 II 680
9.955,57
+12V
1N
4001
470u
0.1u
0.1u
10u
470u
0.1u
0.1u
10u
BAV199
(top view)
3
1
79L12
-12V
Gain = 1+R17/R16
= 22.4
2k2
+
C11
0 1
100mV / 10V
Reed relay
DIP9051-L
12V
R4
2
C12
47
+12V
7
3
2k2
R15
30mV / 3V
D1
1
2k2
R19
10mV / 1V
C7
10
R6
C2
330n
250V~
Chassis
PE
1
6
2k15
C4
2n2
D2b
BAV199
90k
R2
10k
C3
30p
P2, 5k
multi turn
10dB steps
3.162mV
10mV...
14
100R
R22
2k2
R18
C8
0 1
2
P3, 1k
multi turn
Adjustment:
Input to GND
P1: IC1 offset = 0V @ Pin 6 of IC1
P2: Meter offset Null
C3: Input square signal e.g. 1kHz, flat response @ Pin 6 of IC1
P3: Calibrate Meter with sine signal 1kHz
P2: Check Meter offset again