58
Circuit 33:
Peak VU meter with coil-moving instrument
Setup information
Install the transistor and the diode as shown in
Fig. 2.33.
Then install the three resistors and the electro-
lytic capacitor. The three jumper wires come next. Check the placement on the board again and only then
connect the battery. Connect the circuit input to the loudspeaker output of an audio amplifier – but only if
you are familiar with the relevant safety guidelines on working with devices that are to be connected to the
mains as per VDE and know how to observe them.
Components required:
1 x 2N3904 transis-
tor, 1 x 1N4148 silicon
diode, 1 x moving-coil
instrument,
1 x 100
Ω
resistor,
1 x 220
Ω
resistor,
1 x 100 k
Ω
resis-
tor, 1 x 10 μF elec-
trolytic capacitor,
1 x breadboard, 1 x 9V
battery with clip con-
nector
Fig. 2.33:
Peak VU meter
with coil-moving instru-
ment
Experiment
Even if everything is wired correctly, nothing will happen at first; the coil-moving instrument has nothing
to show. If the audio amplifier delivers a signal, the instrument needle will swing as per volume. The scale
could be calibrated in watts output power. Return travel is a bit delayed by means of the electrolytic capaci-
tor C1. Short pulses can thus still be displayed.
The circuit diagram for this experiment is shown in Chap. 3, Fig. 3.33.
Содержание ELECTRONICS EXPERIMENTS BOX
Страница 4: ......
Страница 251: ...253 Fig 3 27 Circuit 27 4 seconds switch off delay Fig 3 28 Circuit 28 20 seconds switch off delay...
Страница 258: ...260 Fig 3 42 Circuit 42 Active 8 5V battery monitor Fig 3 43 Circuit 43 Active 7 8V battery monitor...
Страница 260: ...262 Fig 3 46 Circuit 46 Meters for 1 5 V Zener diodes and higher Fig 3 47 Circuit 47 Discreet 2 2V Zener diode...
Страница 261: ...263 Fig 3 48 Circuit 48 Discreet 2 9V Zener diode Fig 3 49 Circuit 49 Discreet 3 7V Zener diode...
Страница 265: ...267 Fig 3 56 Cir cuit 56 Audio limiter Fig 3 57 Circuit 57 Amplifier for a storm detector...
Страница 269: ...271 Fig 3 64 Circuit 64 Stabilizer for 1 9 V Fig 3 65 Circuit 65 Stabilizer for 2 5 V...
Страница 275: ...277 Fig 3 80 Circuit 80 Quiztimer 30 seconds Fig 3 81 Circuit 81 Handy diode tester...
Страница 290: ...292 Fig 3 118 Circuit 118 HF watch dog with LED indicator Fig 3 119 Circuit 119 HF watchdog with moving coil instrument...
Страница 295: ...297 Fig 3 130 Circuit 130 4 seconds switch on delay Fig 3 131 Circuit 131 15 seconds switch off delay...
Страница 298: ...300 Fig 3 136 Circuit 136 NAND gate with moving coil instrument Fig 3 137 Circuit 137 Input level Mixing console...
Страница 300: ...302 Fig 3 140 Circuit 140 Electrometer with moving coil instrument Fig 3 141 Circuit 141 Simple AM Radio...
Страница 315: ...317 Fig 3 179 Circuit 179 HF generator 150 kHz Fig 3 180 Circuit 180 HF generator 420 kHz...
Страница 324: ...326 Fig 3 202 Circuit 202 3 seconds switch on delay Fig 3 203 Circuit 203 7 seconds switch on delay...
Страница 325: ...327 Fig 3 204 Circuit 204 Piercing siren sound with Piezo element Fig 3 205 Circuit 205 Discrete Operational ampli fier...
Страница 328: ...330 Fig 3 210 Circuit 210 Discreet 5 2V Zener diode Fig 3 211 Circuit 211 Discreet 7 4V Zener diode...
