A large number of R/C modelers are electronics literate to a certain extent. Those who have an understanding of electronics can easily gain the three (3) missing channels of their typical 4 - channel transmitter if it uses a Phillips NE5044 or the older Signetics number CD8081.

To enable an additional channel, one of the pins, either 5, 6, and 7, must be freed. These pins are grounded by Futaba to disable the unused channels. Once freed, components can be added to utilize the channel.

To add a simple on/off type channel, the schematic in Figure 1 is used with the components listed in the table.

1. Pin refers to the freed pin.
2. All wattages can be 1/8W.
3. +Vreg is the regulated voltage output from pin 15.
4. Keep C1 and R3 close to the pin.
5. Switch should be selected to fit the holes that are normally provided for mounting.

Figure1

Component List

LEGEND	DESCRIPTION
C1	0.01 uF Capacitor
R1	39K Ohm Resistor
R2	3.3K Ohm Resistor
R3	10K Ohm Resistor
R4	4.7K Ohm Resistor
R5	39K Ohm Resistor
R6	2.2K Ohm Resistor
S1	SPDT Switch

This same circuit can be used for a low/mid/hi type of channel by substituting a three-position switch with NC/NO. To add a proportional type channel, the switch and resistors R2 and R6 are replaced with a 5K Ohm potentiometer.

The cost of this modification should be under $5 per channel.