IMPACT// ROBOTICS LEAGUE //
UP NEXTIRL Fall Brawl2026-10-24 · Sierra College, RocklinEvent page →
Build · Electronics & wiring

Six components, one power path.

Every plastic-ant bot is the same circuit wearing a different chassis: battery → switch → ESCs → motors, with a receiver telling the ESCs what to do and a light telling the world it’s alive.

LiPo battery (XT30)
  └─→ power switch / removable link   ← the rules-required disconnect
        ├─→ dual brushed ESC ──→ left + right drive motors
        ├─→ weapon ESC ──→ weapon motor   (wedges: skip)
        └─→ receiver  ← powered by the drive ESC's BEC; signal wires to both ESCs

Everything downstream of the switch. Keep the receiver antenna away from motors and carbon.

A proven example system

These combinations have worked well together for our builders. Verify current stock and pricing before ordering; components change.

Example system

  • Drive: 2× Repeat Mini Mark II + Repeat Budget Dual ESC
  • Weapon: RS2205 motor + ReadyToSky 35A ESC
  • Control: FlySky FS2A receiver
  • Power: FingerTech screw switch + 3S LiPo

Acceptable alternatives

  • Drive motors: Turnabot / Malenki N20 motors
  • Drive ESCs: FingerTech tinyESC or compatible
  • Complete kits: SCAR electronics from Team Malice
  • Suppliers: Repeat Robotics, FingerTech, Team Malice, Palm Beach Bots, Bristol Bot Builders

Soldering fundamentals

Master these basics to make connections that don’t fail mid-fight. Use suitable supervision and safe work practices.

Iron setup

  • 360 °C for lead-free solder
  • 340 °C for leaded solder
  • Keep the tip shiny — clean with a brass sponge
  • Tin the tip before each joint

Technique

  • Pre-tin all components (wires, pads, terminals)
  • Heat the joint, not the solder
  • Use flux when solder won’t stick
  • Let joints cool without moving

A good external reference: the Midwest Robot Combat quick soldering guide ↗.

The wiring sequence

Four phases, in order — each builds on the last.

Phase 1

Preparation

Set up the iron, pre-tin every connection point (wires, pads, terminals), and solder the receiver pins properly.

Phase 2

Drive system

Enable mixing on the dual ESC (the critical step), wire the drive motors with correct polarity, and test both drive directions.

Phase 3

Weapon system

Connect the brushless motor to the weapon ESC, complete the ESC arming sequence, and test direction (swap any two of the three wires to reverse).

Phase 4

Power & safety

Build the main power harness, wire the power switch correctly, and verify every connection before first power.

First power goes through a smoke stopper. A smoke stopper (a fused/bulb-limited power lead) is the mandatory first step before full battery power — it catches shorts before they cook your ESCs. Then bind the receiver, verify the fail-safe, and work the functional checklist.

Fail-safe: the test that matters

With the robot secured in containment and the weapon disabled, turn the transmitter off. All motion must stop immediately. If anything keeps moving, the fail-safe isn’t configured, and the bot will fail inspection. Most receivers set fail-safe from a button or via the bind procedure — do it once, verify it every event morning.

Before first full power

  • Smoke-stopper test passed.
  • Polarity checked at every connector with a multimeter — reversed polarity kills ESCs instantly.
  • No conductive debris in the chassis (shake test, then look).
  • Battery secured, terminals insulated, nothing protruding into its bay.
  • Then, only inside containment, follow the functional safety test procedure, step by step.

Common problems, quick fixes

ProblemMost likely causeFix
One motor not spinningLoose solder jointCheck the motor solder joints; test the motor on another channel.
Robot only turns OR only drives straightESC mixing not configuredEnable mixing on the drive ESC — the critical setup step.
Receiver not poweringBEC connection issueVerify the ESC BEC output and check plug polarity.
ESC won’t armBinding or signal problemRebind the receiver; check the signal cables.

Deeper diagnosis lives in the troubleshooting guide.

Learn the skills

External tutorials for the core techniques. The current IRL construction and safety rules always control; do all powered checks in a compliant test box or arena.

Basic Soldering Lesson 1: Solder & Flux ↗

Foundation techniques for solder, flux, heat, and reliable joints.

Combat Robot Electronics for Beginners ↗

A practical introduction to the electronics used in small combat robots.

FPV Soldering Tutorial ↗

Detailed soldering technique that transfers well to compact robot electronics.

Combat Robot Radio Failsafe Tutorial ↗

Radio fail-safe setup and testing for combat robots.

Next: assembly →Testing procedure