Prepare the bench
- Soldering iron and stand
- Wet sponge or tip cleaner
- Lead-free solder
- Small pliers and wire cutters
- Screwdrivers and tweezers
Interactive electronics resource
Electronics Construction Guide
A practical guide to identifying, fitting and soldering the common components used in MitchElectronics kits.
IdentifyMatch the component and PCB reference.
OrientCheck polarity and package direction where required.
SolderHeat the pad and lead together, then feed the joint.
InspectCheck every joint before applying power.
01 / Getting started
Before you start
Good construction starts before the soldering iron is switched on. Identify the parts, PCB references and tools you need first.
PRE-FLIGHT
Ready to build?
0 of 5 checks complete
Start with the small parts.
Fit low-profile components such as resistors first. Larger controls, buzzers and connectors are normally easier to add later.
02 / Core skill
How to solder
A good joint is made by heating the PCB pad and component lead together, then allowing solder to flow across the connection.
Step 1 of 6
- Fit the component.Place it in the correct PCB position and keep it stable when the board is turned over.
- Clean the iron tip.A clean, tinned tip transfers heat quickly and consistently.
- Heat pad and lead together.Touch the iron to both surfaces so the joint, rather than just the solder, reaches temperature.
- Feed solder into the joint.Apply solder close to the iron and allow it to flow around the component lead and pad.
- Remove solder, then the iron.Give the solder a moment to finish flowing and let the joint cool without movement.
- Trim the lead.Cut the excess lead just above the finished joint and control the offcut as you trim it.
03 / Assembly order
Build from low to high
Working from the physically smallest parts to the tallest keeps the PCB accessible and makes it easier to hold components in place.
Select a stage to jump to the relevant component guidance.
04 / Component guide
Find the part you are fitting
Search by component name or PCB reference. Open only the sections you need for the kit in front of you.
R ResistorsFit early · no polarity
Resistors are normally fitted early because they sit close to the PCB and are among the smallest through-hole components. The schematic and PCB use the same R-number.
- Identify the required value and reference.
- Push the resistor in so the body sits close to the PCB.
- Solder each lead from the underside.
- Trim both leads above the joints.
Reference matching
The resistor value tells you what to fit; the R-number tells you where to fit it.
CCapacitorsCeramic & electrolytic · check polarity where marked
Ceramic capacitors
Match the C-number to the PCB. Ceramic capacitors in this guide are non-polarised. Fit them a few millimetres above the PCB, solder both leads and trim the excess.
Electrolytic capacitors
Electrolytic capacitors are polarised. The positive lead is normally longer, while the negative side is marked by a stripe on the body.
Check before soldering
The PCB example uses a square pad for positive. Confirm both the component and PCB marking before making the joint.
DDiodes & LEDsPolarised · cathode/anode orientation matters
Diodes
The band on a diode marks the cathode side. Match the band to the cathode indication on the PCB outline.
LEDs
The longer lead is the anode and the shorter lead is the cathode. Do not trim the leads until the LED has been fitted and soldered.
PCB example
In the source board shown here, the square pad is the cathode and the round pad is the anode.
SSwitchesS / SW · package often sets the orientation
Switches are commonly identified with S or SW followed by a number. Tactile switches have formed legs that click into the PCB when fully inserted, helping them sit flat before soldering.
Seat the part first
The retaining-leg click is a useful sign that a tactile switch is fully inserted.
QTransistorsOrientation matters · avoid unnecessary heat
Transistors are identified with Q followed by a number. The kits described in the source guide commonly use TO-92 devices. Match the curved and flat sides of the package to the PCB outline.
- Confirm the reference and package orientation.
- Insert all three leads without forcing them.
- Solder efficiently and avoid dwelling on a lead.
- If needed, use a small crocodile clip on the leads as a temporary heatsink.
URegulatorsTO-92, TO-220 and SMD examples
Through-hole regulators
Regulators are integrated circuits and use U or IC references. TO-92 parts are fitted much like transistors. TO-220 packages are larger and easier to hold while soldering.
Surface-mount regulator
For the AMS1117-style example, tin the large tab pad first. Hold the device in position with tweezers while reheating that pad, then solder the three smaller leads once it is secured.
ICIntegrated circuitsUse the socket · align all three notches
IC sockets allow the socket to be soldered first and the IC to be inserted only after the rest of the circuit has been assembled.
- Insert the socket and align its notch with the PCB marking.
- Solder two opposite corner pins.
- Check the socket is flat; reheat those joints if adjustment is needed.
- Solder the remaining socket pins.
- Insert the IC after construction, with its notch matching the socket and PCB.
Three notches, one direction
PCB outline, socket and IC should all indicate the same orientation.
RVPotentiometersFit later · keep the control accessible
Potentiometers are identified by RV followed by a number. Larger types are usually fitted later. Their orientation matters mainly because the shaft or adjustment point must remain accessible.
Insert the part, turn the PCB over and let the board rest on the component while soldering. Small trim potentiometers usually fit in only one physical orientation.
BZBuzzersOften polarised · normally fitted late
Buzzers are typically identified by BZ. For a polarised buzzer, the positive connection can be identified by the longer lead or a plus mark on the body.
Passive buzzers
Some buzzers are not polarised and may have equal-length pins. Check the kit instructions when the part is not marked.
MKMicrophonesElectret · inspect the underside for polarity
The electret microphones shown in the source guide are polarised. Their leads may be equal length, so polarity is identified from the underside.
The lead connected by small traces to the metal case is the negative connection. The other lead is positive. In the PCB example, positive is fitted to the square pad.
Look underneath before fitting
Lead length is not a reliable polarity cue for these microphones.
LSSpeakersObserve polarity in multi-speaker systems
Speakers are marked with positive and negative terminals. Polarity is most important when multiple speakers need to move in phase; for a simple single-speaker kit it is generally less critical.
Protect the fine coil wires
Do not solder to the delicate contacts carrying the tiny wires into the speaker coil. Use the intended external solder pads.
P/JWiresPower, inputs and outputs · use colour consistently
Wires connect the finished circuit to power, inputs and outputs. Connection points are often marked with P or J references.
Red
Recommended for positive supply connections such as VDD and VCC.
Black
Recommended for GND, VSS and 0 V connections.
Use colour consistently
Consistent power wiring makes the final assembly easier to inspect and reduces ambiguity.
No component matches that search.
Try a name such as LED, capacitor, or a reference such as Q or RV.
05 / Before power
Inspect the completed board
A few deliberate checks before applying power can catch most assembly mistakes without any fault-finding.
READY TO BUILD
Then return to your kit instructions.
Use this guide whenever you need to confirm a reference, orientation or fitting method.
Keep learning
Build the circuit. Then understand it.
Return to the resource library for kit instructions, circuit explanations, calculators and other practical electronics guides.