238
Circuit 213:
Improved detector receiver
Setup information
Install the diode, the fixed value inductor and the two electrolytic capacitors as shown in
Fig. 2.213
fol-
lowed by the four jumper wires. Last but not least connect the Piezo element. Check the placement on the
board again.
You can significantly increase the sensitivity of the Piezo element by using a sound plate or even a sound
box. Read more about it in Chap. 1.2.3
Components required:
1 x BAT85 Schottky
diode, 1 x 1 nF ceramic
capacitor, 1 x external
ceramic capacitor (see
Experiment for value),
1 x 220 μH fixed induct-
ance, 1 x Piezo element,
1 x breadboard
Fig. 2.213:
Improved
detector receiver
Experiment
A detector receiver is the bedrock in radio technology. This receiver circuit was already in use more than 100
years ago. Its signature is that no battery is needed for operation. Receiver and headphone are merely pow-
ered by a wire antenna, which should be as long as possible. A ground connection as short as possible is
made to a water line. For the capacitor in parallel to the fixed value inductor, we recommend a small wire
capacitor (approximately 200 pF) that you may have in your crafting box. Alternatively, experiment with
all sorts of parallel and series combinations using 10 pF, 100 pF or 220 pF ceramic capacitors. One of these
combinations should offer favourable conditions for a clear reception of the nearest local broadcaster on
MW. At night you should be able to receive several other strong stations.
The circuit diagram for this experiment is shown in Chap. 3, Fig. 3.213.
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...
