- on Test & Measurement
- Published in issue 12/2002 on page 0
using a CMOS timer
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.
Elektor recommends its business partner Eurocircuits as the company of choice for its own prototypes and volume production in selected cases.
R1 = 390?
R2 = 22M?
R3 = 2M?2
R4 = 220k?
R5,R9 = 22k?
R6 = 2k?2
R7 = 220?
R8 = 1k?
P1 = 2M?5 preset
P2 = 25k? preset
C1,C2,C4 = 100nF
C3 = 10µF 63V radial
C5 = 47µF 16V radial
D1,D3 = zener diode 5V6, 500mW
D2 = LED, red, high-efficiency (2mA)
T1 = BF245A or BF256A
IC1,IC2 = 555C or TLC555 (CMOS 555)
S1 = rotary switch, 2 poles, 6 positions
S2 = pushbutton, 1 make contact
K1,K2 = 4-way SIL socket for IC pins, turned pins
Case, 60 x 10 x 126 mm with battery compartment
Moving coil meter, f.s.d.100 µA