Construction - Soft Starter for Power Tools - PCB layout

Oct 12, 2026

Upload by hdkawk

Detailed construction guidance for a Soft Starter for Power Tools, including Fig.6 overlay diagrams and installation orientation of components such as diodes, electrolytic capacitors, and IC1. Covers PCB preparation on a 59mm×80.5mm double-sided board, handling of the 0.012 SMD resistor underside, securing CON1 with machine screws, and wiring precautions. Explains neutral reference sensing via CON1 Nin, separation of ground paths around D3/D4 and pin 3, and the electrical separation between high-voltage 230V AC and low-voltage ±12V sections.

LanguageEnglish

CategoryTechnology

FormatPDF

Pages1

Reading Time3 min

AccessFree to download

Construction

PCB layout

Constructional Project Fig.6:use these overlay diagrams and the photograph below as a guide when building the Soft Starter.Just one component,the 0.012 SMD resistor,goes on the underside.The diodes,electrolytic capacitors and IC1 must be installed with theorientations shown here.Multiple pads are provided to suit differently sized X2 capacitors.Secure CON1 with a machinescrew at each end before soldering its pins. The relay gets close to the full 24Vacross its coil initially to turn it on,but the 220μF capacitors then partiallydischarge.The reduced coil voltage issufficient to keep it energised and therest of the circuit will run happily with±6V or less.When the relay turns off,the 220μF capacitors charge back up totheir original level. that the ±3.3mV references track thisground potential accurately or the unitwon't work properly. and 330nFX2 capacitor,all other tracksare clear of those pins.There can alsobe a fairly high voltage across TH1 andTH2 when they are conducting,so theirterminals are kept clear of other tracks. Therefore,the connection betweenthe cathode ofD3,the anode of D4 andpin 3 of CON1 is separate from otherground paths. # Construction The Soft Starter for Power Tools isbuilt on a59mm×80.5mm PCB,coded10107121.This boardis available fromthe EPE PCB Service.It is a double-sided PCB with tracks on the top side,paralleling the high-current paths onthe bottom to improve its current-handling capability.All componentsare through-hole types,which mounton the top with the exception of the10mΩ resistor,which is an SMD. This way,current flowing throughZD1,ZD2,the 220μF capacitors andother components to ground does not in-terfere with the comparator's operation. # PCB layout While various components in the cir-cuit are shown connected to ground,the main reference point is the 'Nin'(Neutral In)terminal of CON1.Thisis the potential which the shunt sensevoltage is relative to.Because this isvery low (just a few mV),it's critical As is typical with a circuit whichruns directly from mains,the PCB hasa high voltage section at 230V AC anda low voltage section of±12V(relativeto the neutral potential). Since the only components con-nected to live are the 10MQ 1W resistor Here's a view inside the box,fairly close to life-size.You can clearly see the way the wiring is connected to the terminal block on the left end of the PCB-follow this along with the diagram above when wiring it up.If placed inside a metal box, the earth wires must instead be firmly anchored to the box-see text for more details.

FAQs

Which components require specific orientation during construction?

The diodes, electrolytic capacitors, and IC1 must be installed with the orientations shown in the guidance.

How is the main reference point defined for the PCB layout?

The main reference point is the 'Nin' (Neutral In) terminal of CON1, which sets the potential for the shunt sense voltage.

What voltage sections does the PCB include and why does it matter?

The PCB has a high-voltage section at 230V AC and a low-voltage section of ±12V relative to the neutral potential, requiring careful separation to avoid interference.

Oct 12, 2026

Upload by hdkawk