Merg Servo4-F Driver Kit 75 Building Instructions

Servo4-F Driver Kit 75
These are the Kit Building Instructions for the updated Kit 75 Servo4-F Driver Module for controlling model aircraft servos used to actuate turnouts and
signals on your layout. This revised kit incorporates extra components identified as desirable from experience of the original module and includes pull-
up/down resistors for the output servo control lines to counter servo twitch on power-up, separated 5v regulators for the microcontroller and servos to
counter noise and brown-outs, and a full wave bridge rectifier for the power input. Do take a few minutes to read right through these Instructions. It
is also recommended that the builder has read through Technical Bulletin A38/1 which provides a technical introduction to the Servo4 driver board and
how it is configured by using Kit 76, the Servo Setting Box, or an IBM PC. Pay particular attention to the warnings about connecting power
supplies on page 3.

Kit Contents

Ref Component
R6 1K ¼W resistor
R5 10K - 5 pin Resnet
R1 R2 10K ¼W resistor
R7
C3 4.7uF or 10uF/16v
tantalum capacitor
BR1 DIL Bridge rectifier 1A
J1 2-way 5mm term block
J2-J5, 18 pin 2.54mm PCB
LK1, LK3 Header
LK1, 2.54mm jumper link
LK3
Circuit Diagram of the Servo4 Driver Board
'Static' caution. Before opening any kits, touch a nearby radiator, tap, or other earthed metal and then try to stay seated while the kit is
opened and assembly undertaken. Leave the 'SRV4 microcontroller' on its protective conductive foam until ready to install.

Assembly

1. Fit resistors R6* (1K); R1, R2 and R7 (10K ) and R4 (100K). Beware these resistors look very similar to the untrained
eye and in poor light. Also, depending on supplied stocks, could be either 3-band resistors with a light cream body or 4-
band resistors with a blue body. The following table illustrates the differences:
75Servo4-F Bldinst2c.doc
No. in Ref Component
kit
1 R4 100K ¼W resistor
1 D1 Diode 1N4002
Black plastic body-silver band
3 C1 1000uF/16v electrolytic
capacitor
1 U3 78L05CV 100mA TO92 voltage
regulator IC
1 (U1) 14 pin DIL socket for U1
1 J7 9-way D-type pcb skt
1 LK2, 50mm 24swg tinned Copper
ICSP
2 J8 6 pin 2.54mm PCB ICSP
1 of 4
– Building Instructions
No. in
kit
1
1
1
1
1
1
1
wire
1
header
Issue 2c
June 2012
Ref Component
R3 2K2 - 8 pin ResNet
D2 D3 Diode 1N4148
glass body-black band
C2, C4 100uF/16V electrolytic
capacitor
U2 7805 1A TO220 voltage
regulator IC
J6 3-way 3.5mm term blk
Printed Circuit Board
'Servo4 rev F'
U1 PIC 16F630 (SRV4)
microcontroller
June 2012
No. In
kit
1
2
2
1
2
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