LED Bedside Lamp
with turn-off delay
If you are not lucky enough to have access to expensive test gear then lamp circuits using LEDs offer a good chance of success and allow a little bit of electronic experimentation. One of our readers has come up with this simple but useful addition to the bedside table. The lamp is activated either by pressing a push button or automatically when the in-built microphone detects a noise.
Materials
Gerber file
CAM/CAD data for the PCB referred to in this article is available as a Gerber file. Elektor GREEN and GOLD members can exclusively download these files for free as part of their membership. Gerber files allow a PCB to be produced on an appropriate device available locally, or through an online PCB manufacturing service.
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Component list
R1 = 15kOhm
R2,R8,R9 = 100kOhm
R3 = 22kOhm
R4 = 5kOhm 6
R5 = 6kOhm 8
R6 = 1MOhm
R7 = 390kOhm
R10 = 10kOhm
R11 = 18Ohm
Capacitors:
C1 = 22nF
C2 = 47µF 16V radial
Semiconductors:
D1 = LED, white, e.g., Conrad Electronics # 153867
IC1 = TLC274
T1,T2 = BC547B
Miscellaneous:
Bt1 = battery holder for 4 NiMH cells
K1 = charge socket for batteries
MIC1 = electret microphone capsule
S1 = pushbutton, 1 make contact
PCB, ref. 030122-1
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