© <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), complete with simulated damage affecting speed and variable weight classes. In addition, the DBC offers momentum simulation, and options to disable the "super-spin" feature and recoil while firing. A DBC requires either an Tamiya TBU, or a DBU sensor if battling is desired. A DBC is available in kit form.

This model of DBC (DBC HL) works with the stock Heng Long Smoke&Sound ESC&sound board (TK-RX13/TK-RX14/TK-RX18) and Heng Long Radio.

NEW: Version 1.6 with recoil blocking option! When enabled and firing, the Heng Long tank does not stop, jerk, or play the stock Heng Long firing noise, but instead plays a sound from the sound effect chip (if installed). Bypass option and momentum config jumper removed (jumper used for recoil option).


Build instructions for DBC kit
Build instructions for DBU kit
Adding sound to version 1.5+
Instructions for connecting to the TK-RX18 board

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.

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

Features for current version:

  • Accepts hits using Tamiya standard signal and lights up "hit" LEDs
  • Fires IR shots using "K" button with standard sound and recoil (or custom fire sound with recoil disabled).
  • Supports optional sound chip for "hit" and "death" signals played through Heng Long speaker or separate speaker (same sound for "hit" and "death" when recoil disabled)
  • 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
    • -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 default
    • -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)
    • -can (en/dis)able recoil blocking
  • 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

  • Recoil blocking can be enabled by placing a jumper over the "rec" pin
  • 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", "Block Recoil" and "Momentum" can be set.
  • To enable momentum, push the left joystick up.
  • To disable momentum, push the left joystick down.
  • To enable super-spins, push the left joystick left.
  • To disable super-spins, push the left joystick right.
  • To enable recoil blocking, push the "K" button.
  • To disable recoil blocking, push the "G" button.
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.

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.

Recoil Blocking:
When the firing button is pressed while the "block recoil" feature is enabled, the IR signal is sent as normal, but the tank doesn't jerk or play the default sound effect. In order to maximize realism and battling fairness, the DBC instead plays a sound effect from the sound effect chip...this means that there is only one other sound effect available so it's played for both "regular hits" and the final "destruction hit". As a side benefit, the same electrical signal used to trigger the "firing" sound could also be used to optionally trigger a flash unit or cannon recoil unit.
If "block recoil" is left disabled (the default) the recoil and stock Heng Long sound functions normally, and the DBC plays a separate sound for both "hit" and "destruction".

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.

Previous Version 1.5 specs