Ballast Tank Switch Proportional UNIpro 12V

This control unit allows proportional control of a Piston Tank, e. g. the piston is driven to a position set by transmitter. The exact position is detected by a so-called Hall effect sensor connected to the UNIpro by a wire and switched through magnets mounted on to one of the Piston Tank's gear wheels.

As control device on the transmitter a proportional or rotary slider can be used. The UNIpro is compatible to most customary R/C systems (accepted receiver signal 0.7 to 2.3 ms).

The UNIpro can be operated in two different modes. In the first mode, called 20/80, the first 20% on the slider of the transmitter control the first 70% of piston movement.  The last 80% on the slider control the last 30% of piston movement. This mode allows precise trim of the boat and is preferable for most Piston Tank volumes. In the second, so-called linear mode the entire Piston Tank volume is controlled on the slider. This only makes sense for Piston Tank volumes with less than 300 ml, as resolution of the slider is otherwise too low to allow for exact adjustment.

The control current for the unit is fed in by the wire lead connecting  to the receiver. Receiver current should be 4.8 to 6 V as common for most R/C components. The UNIpro can take currents up to 8.4 V. However, most servos and receivers cannot bear such high voltage. Operating current depends on Piston Tank (6 or 12 V) used and supplied by the main battery.

The Piston Tank used must feature end switches for safe termination of piston movement at its corresponding end positions (e. g. completely full or empty). All ENGEL Piston Tanks are equipped with such end switches.

With the optional Pressure Switch (DS) connected, maximum depth is limited to approx. 1.8 meters (5.9 ft). If the model dives below this level, the UNIpro will automatically switch to the "bail" and empty the tank. The model will then resurface if the slider is also set to "bail". Otherwise, with the slider left in its initial position the model will emerge to a depth above 1.8 meters after which the tank will start filling again until the piston has reached the position according to the slider.

Furthermore, the Pressure Switch (DS) acts as a second security device. Should the over pressure which builds-up within the hull while submerging (by filling the tank) be lost due to a leakage, the "submerge mode" will be terminated by the switch. In this case, the red LED flashes steadily, and the system does not allow the model to submerge again until this has been corrected. Alternatively, the UNIpro offers another fail safe device. If the transmitter signal is lost - due to increased depth or other circumstances - the UNIpro will switch to "blow" (empty) the Piston Tank.

The UNIpro also offers a so-called Battery Voltage Monitor. The voltage of the main battery is permanently verified. Should voltage fall below a specific threshold value for more than 5 seconds, the unit will switch to "bail". Threshold value is factory set to approx. 4.5 V for 6 V operation or about 9 V for 12 V operation (adjustable). Low battery mode is indicated by lighting of the red LED.

Connecting and Fitting Hall Effect Sensor and Magnets
Position of the piston within the tank is detected by a Hall effect sensor pre-fitted on a separate board and connected to the UNIpro by a three-wire lead. Position and attachment of the sensor depends on the particular Piston Tank.

The Hall effect sensor is actuated by magnets. The UNIpro comes with two pairs of dice shaped magnets, two  Neodymium (nickel-plated) and two ferrite (black) magnets. Additional magnets in various sizes and shapes are optionally available.

A pair of magnets mounted to the main gear wheel (spindle) allows an accuracy of half a rotation. Mounted to the middle gear accuracy is already multiple. Using 2 pair of magnets will result in duplication of accuracy. For Piston Tanks in 6 V with 540 size motor as well as 12 V with 380 size motor the middle gear wheel is ideal for mounting up to 3 or 2 pair of magnets respectively. On a 6 V/540 tank drive the Hall sensor can be screwed directly to micro switch S1. On a 12 V/380 tank drive the middle gear is more distant to S1. To bridge this distance a bracket (i. e. bend from a piece of brass) can be used for reaching the necessary proximity of sensor to magnets.

The middle gear wheel of a Piston Tank in 12 V and 540 size motor is rather small. For this type of tank the main gear wheel (with spindle bushing) is a better alternative. 3 pair of disc shaped Neodymium magnets 1.5 x 0.5 mm (item no. 5810-1510) will allow for accurate trim. The Hall sensor can be attached (i. e. glued) to micro switch S1.

Technical Specifications

Set includes
1 Piston Tank Control Unit UNIpro
1 Hall effect sensor mounted to PCB with connection lead
2 pair of Neodymium magnets 3 x 3 mm
3 spacers 5 mm
3 screws A2 2.9 x 9.5 mm

Low-Battery-Monitor pre-adjusted to approx. 9 V for 12 V operation.