Soft Start for Amplifiers
saves fuses and electronics

This is a MEMBER ONLY article. You need a subscription to read this article.
- Access to Elektor archive and 5,000+ Gerber files
- Receive up to 8 magazines per year (digital and/or paper)
- 10% discount in the Elektor store
Available from €4.95 per month.
What is Members Only
Elektor is committed to providing high-quality content on electronics, catering to tens of thousands of paying members. As part of this commitment, Elektor has launched Premium, an initiative that offers exclusive online articles to members sometimes even before they appear in the magazine.
Every day, members can access in-depth articles that showcase the best of Elektor's premium content.
This initiative aims to reward members with early access. Once logged in, members can easily enjoy this exclusive content and engage in discussions about featured projects. While Premium adds to the existing resources available, Elektor will continue to provide a wealth of free information.
Join the Elektor community today to take advantage of Premium and other benefits!
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.
Elektor recommends the Elektor PCB Service service from its business partner Eurocircuits or AISLER as the best services for its own prototypes and volume production.
The use of our Gerber files is provided under a modified Creative Commons license. Creative Commons offers authors, scientists, educators and other creatives the freedom to handle their copyright in a more free way without losing their ownership.
Components
The BOM (Bill of Materials) is the technically exhaustive listing of parts and other hardware items used to produce the working and tested prototype of any Elektor Labs project. The BOM file contains deeper information than the Component List published for the same project in Elektor Magazine. If required the BOM gets updated directly by our lab engineers. As a reader, you can download the list here.
Want to learn more about our BOM list? Read the BOM list article for extra information.
Component list
Components List
Resistors
R1,R3 = 33Ω carbon film, 5%, 0.25 W, 250V
R2,R4,R25,R26 = 680Ω carbon film, 5%, 0.25W, 250V
R5 = varistor, Epcos B72210S2271K101 (for 230VAC mains voltage) *
R5 = varistor, Epcos B72210S2151K101 (for 115VAC mains voltage) *
R6.R7 = NTC 16Ω, 2.1W, Epcos B57236S160M (for 230VAC mains voltage) *
R6 = NTC 16Ω, 2.1W, Epcos B57236S160M (for 115VAC mains voltage) *
R7 = wire bridge (for 115VAC mains voltage) *
R8,R14 = 25Ω, 1%, 15W, T)-126, Caddock 915
R9,R10,R15,R17 = 22kΩ carbon film, 5%, 025W, 250V
R11 = 470Ω carbon film, 5%, 0.25W, 250V
R12,R13,R18,R19 = 100kΩ carbon film, 5%, 0.25W, 250V
R16,R22 = 4.7kΩ carbon film, 5%, 0.25 W, 250V
R20,R21 = thermistor, ICL NTC, 10 Ω, -20% to +20%, radial, Ametherm SL15 10006
R27,R28 = 220Ω metal film, 1%, 0.6 W, 350V
Capacitors
C1,C3,C6 = 470µF, 50 V, 5mm pitch (13x21 mm)
C2,C4,C7 = 47µF,100V, 5mm pitch
C5,C9,C10,C11 = 100nF, 50V, X7R, 0.2’’ pitch
C8 = 1nF, 100V, X7R, 0.2’’ pitch
C12 = 4.7nF, X1/Y1, 500V, Y5U, 15mm pitch
Semiconductors
D1–D4 = 1N4148
B1 = bridge rectifier 600V, 4A, GBU405
LED1,LED2 = green, 3mm
T1,T2 = BC337
IC1 = 7805 (+5V, 1A)
IC2 = 7818 (+18V, 1A)
IC3 = 7918 (–18 V, 1A)
IC4 = ATTiny44-20PU microcontroller, programmed, Elektor Store no. 170462-41 *.
IC5,IC6 = TLP222A-2 double optocoupler
Miscellaneous
K1,K9,K11 = 2-way PCB screw terminal block, 0.3’’ pitch, 630V
K2 = 8- way PCB screw terminal block, 0.2’’ pitch(300V)
K3 = 6-way 2-wire PCB terminal, Wago 806-106 *
K3 = matching 6-pin header, Wago 806-906 *
K3 = 6-way PCB screw terminal block, 0.2’’ pitch, 300V, e.g. Multicomp MC000039 *
K4,K5,K6,K8 = 3-pin pinheader, 0.1’’ pitch w. matching cable parts
K7 = 2-pin pinheader, 0.1’’ pitch w. matching cable part
Shrink connector 1-pole, minimum 14 pieces
TR1 = safety transformer, 1.5VA, primary 2 x 115V, secondary 2 x 6V, e.g. Block AVB1.5/2/6
RE1,RE2 = power relay, SPDT, 12VDC, 16A, through-hole (Omron G2R-1-E 12DC)
RE3,RE4 = power relay, DPDT, 24VDC, 8A, non-locking (Omron G2RL-24-CF-DC24)
GRV IR receiver (Seeed)
60°C thermostat, e.g. Thermorex TK24-T02-MG01-Ö60-S50
PCB no. 170462-1 (v2.21) from Elektor Store
* see text
Discussion (0 comments)