© <in der past>
David's Battle Circuit (DBC) & David's Battle Unit (DBU)

The DBC is a Tamiya compatible battle circuit for Heng Long S&S tanks. It allows Heng Long owners to particpiate in battles using infrared "bullets" on an equal footing with Tamiya Full-Option tanks equipped with Tamiya Battle Units (TBU). In addition, the DBC offers momentum simulation, and an option to disable the "super-spin" feature. A DBC requires either an Tamiya TBU, or a DBU. A DBC is available in kit form.
The DBU is a TBU compatible IR detector and hit indicator. It can be mounted on Tamiya Full Option tanks, or on DBC equipped Heng Long tanks. It is available in kit form, and requires the user to provide their own connecting and mounting hardware. Additionally, filtering is recommended for outdoor use.

Version 1.5 with sound! A sound chip capable of storing and playing back 2 x 20 second or shorter user customized sound clips can be added to version 1.5 kits. The modifications are fairly simply, but remove the option to enable/disable super spins by a jumper (the default is spins disabled, and this can be overridden using the TX at startup time).

Note that these units are KITS and require the assembler to have basic soldering skills and tools.

As of September 2007, I did another limited production run and two kits remain unsold. If you're interested, email me at darkith /@/ gmail \dot\com.

Current prices:
DBC kits $40USD
DBU kits $15USD
Sound chips $15USD
S&H in North America is $10USD, contact for International.
Payment by Paypal

Assembled DBC version 1.0 with IR LED from DBU kit

Assembled DBU version 1.0

DBU custom-installed on PzIII. IR LED has replaced the red airsoft warning LED. Note that mounting and filter is not included.

Very nice custom install job done by Matt. Mounting parts and filters are not included.

Build instructions for DBC kit
Build instructions for DBU kit
Adding sound to version 1.5

Version 1.0 DBC+DBU without sound videos
PzIII kills ShermanSherman (with sound off) kills PzIII
Version 1.5 DBC+DBU+soundchip videos
HL PzIII against FO Sherman (with muted sound) HL PzIII against FO Sherman


  • Accepts hits using Tamiya standard signal and lights up "hit" LEDs
  • Fires IR shots using "K" button with standard sound and recoil.
  • Version 1.5+: supports optional sound chip for "hit" and "death" signals played through Heng Long speaker or separate speaker
  • Adjustable weight classes (superlight, light, medium, heavy) set by jumpers, which affects
    • -damage (1, 3, 5, 9)
    • -reduction in speed when damaged (approx50%@1,1,1,1) (approx25%@1,2,3,5)
    • -reload times (2, 3, 5, 9) in seconds
    • -15 seconds from death to mobility (engine shuts down on destruction, restarts and ready to move after 15s)
    • -temporary invulnerability after death (20 ,15, 12, 10) in seconds
  • Momentum/inertia option enabled by jumper
    • -affected by weight class
    • -slow acceleration
    • -coasts to a stop
    • -soft braking (partial opposite stick)
    • -hard braking (full opposite stick)
  • Super Spin disable option
    • Enabled by jumper (only in version 1.0)
    • Enabled by default in version 1.5+
    • -disables super spin completely
    • -allows much smoother control of skid-turning at low speeds and when accelerating into a turn from rest
  • Radio failsafe: sets tank to neutral after losing radio signal for ~1/4second
  • Remote config after power on (until ignition pressed)
    • -overrides jumper settings
    • -cleared by power-cycling
    • -can (en/dis)able Momentum
    • -can (en/dis)able Super Spins
    • -useful for having "realistic" motion for recreational driving, but full capability when battling
    • -useful for disabling momentum when driving in confined spaces (protects fragile add-ons)
    • -bypass mode: disables all DBC processing and temporairily returns tank to stock Heng Long operation
  • IR input & hit LEDs interface compatible with Tamiya "apple"/TBU.
  • IR output compatible with standard IR LED (including Tamiya's)
  • Connections consist of
    • -connection in between Heng Long RX and ESC board (cut a jumper wire in half). Easily disconnected to return to stock
    • -5v power wire from Heng Long ESC board
    • -two wire cable to IR LED (DBU version, RadioShack version, or Tamiya version)
    • -five wire cable to DBU or TBU
    • -(optional for sound) four connections to sound chip, one connection from sound chip to HL ESC board

  • To enable momentum, place a jumper over the pins for "MOM". Leave the jumper off to disable
  • (version 1.0 only) To disable super-spins, place a jumper over the pins for "SPN". Leave the jumper off for normal behavior
  • (version 1.5+) Super spins are disabled by default, use the remote config (see below) to change this during startup
  • To configure the weight, place a jumper over the appropriate pins:
    • Super-light: no jumpers
    • Light: jumper on W1
    • Medium: jumper on W2
    • Heavy: jumper on W1 & W2
ClassReload time50% speed at X25% speed at XDestroyed at XMomentumInvulnerability
Super Light2 sec111minimal20 sec
Light3 sec123little15 sec
Medium5 sec135medium12 sec
Heavy9 sec159lots!10 sec

After turning on the tank power switch and TX power switch, the DBC circuit loads the configuration from the jumpers then waits in "remote config" mode until the "Engine Ignition" button (with the key on it) is pressed on the TX. During this time, the configuration for "Super Spin Disable" and "Momentum" can be over-ridden.
  • To force momentum to be enabled, push the left joystick up.
  • To force momentum to be disabled, push the left joystick down.
  • To force super-spins to be enabled, push the left joystick left.
  • To force super-spins to be disabled, push the left joystick right.
To exit config mode with the current configuration, press the "Engine Ignition" button and the tank will start. The config will remain effective until the power switch on the tank is turned off. To change the config, the tank will need to be turned off, then on.
While in config mode, bypass mode can also be immediately enabled by pressing the "K" button (no further config will be posssible). After entering bypass mode, start the tank normally using the "Engine Ignition" button.

Pressing the "K" button will fire the battle system. The DBC will then prevent further shots until the reload period has elapsed (depends on the weight setting of the tank). Pressing the button rapidly may appear to cause 2 shots, but only one actually occurs.
A hit is shown by the LEDs lighting up briefly, during this time the tank cannot fire.
After taking 1 hit, the tank will slow to approximately half speed.
After taking several hits (weight dependant), the tank will slow to approximately 1/4 speed
After taking full damage (weight dependant), the LEDs will light up and stay on to indicate desctruction and the tank engine will shutoff. The headlights will blink. After a few seconds, the tank will being starting up. Once the startup has completed, the LEDs will turn off and the tank will be able to move again. The tank will be temporairily invulnerable for a short period (weight dependant).

The tank will slowly accelerate and decelerate to emulate a vehicle with weight, depending on the weight setting. Braking can be accomplished by pushing the stick half-way in the opposite direction of travel. Hard braking can be accomplished by pushing the stick completely in the opposite direction of travel.

Notes: Users may notice a slight decrease in perceived range (~10%). This is due to the DBC being more selective about what constitutes a valid signal. Accepting a wider range of signals causes the tank to operate oddly, including sporadic triggering of shots and ignition, which may not always be noticeable when not using a battle system.
The DBU requires filtering in order to operate outdoors, otherwise the range will be reduced to mere feet. I recommend trying horizontal baffles similar to the TBU, and using a visible light filter. A simple visible light filter can be made by cutting the dark portion off a developed 35mm film negative. This will absorb most of the visible light while passing the infrared signal through.