1 2 3 4 5 6 7 8

A A

GAIN switch
B Pos. 2 : High Gain B
Pos. 1 : Low Gain
PIN photodiode sensor
GAIN +9V
20k
R9
2M C10
R5
0.1u

220p
C5
QSD2030 C1

+
D1 GND
10u

220u/10V
0.1u
+9V TL072

C2
6
2 TL072 7 IC2

6
1
R6 5 3

GND

C9
1
8
B+ 20k 220R
D2 3 2M IC1B 5

A10k
VOL
C 1N5819 R2 IC1A C6 2 +
C
LM386N-1 C7 220R R3

7
8

C11 220p Headphones output

4
+

R4
C3 C4 0.1u
+

+
20k

220u/10V IC1.PWR
R1

10u GND GND GND 10u GND

B-

10R
R7
GND 2
Transimpedance amplifier (TIA) 1 8 ohm speaker (optional)
SHIELD GND SPEAKER
GND GND

Functional description
D Portable photodiode amplifier with headphone output D
Analog audio receiver for modulated ambient light. Purpose: field recording, ambient listening, audio experiments, art installation, etc.
Fluctuations in the intensity of incident light (visible and near-IR) are amplified and band-limited to audible frequency range.
Analog audio output is available at headphones jack or optional 8-ohm speaker.
For recording, connect phones jack to line in port of any audio recording device

Op amp specification
Requirements for best performance: low noise JFET op amp, max supply voltage >10V
TL072 works

Capacitor specification
For best results avoid Class 2 dielectric (i.e. X7R) capacitors. Use polyester film, electrolytic, or C0G/NP0 ceramic.
Response polarity
TIA output deflects toward GND for increasing illumination when D1 is oriented as shown
LM386 output deflects positive for increasing illumination

Power supply
For 9V battery. Do not exceed 10 volts.
12V operation OK if 16-volt rated capacitors are used for C9, C11 (220 uF).
E E
License Terms
Creative Commons Licence: CC-BY-SA RARE WAVES LLC (USA)
Created by: Eric Archer (Rare Waves LLC USA) 2018
Web: rarewaves.net
Lite2Sound BC
PHOTODIODE AUDIO RECEIVER
FOR AMBIENT MODULATED LIGHT
rarewaves.net
1 2 3 4 5 6 7 8