APPENDIX -A
73
APPENDIX -A
Notice for using Horn Control/Light Control by Function Output Port
The equal value for Function Port
NOTE:
Do not use over 5 Volts DC on the Function Port because this could damage the port.
Example for connecting an external relay circuit
The use of external equipment may require a source current higher than can be supplied directly by the TK-7100H /
8100H function output port. The circuit below shows a method for supplying the additional current required to activate
the relay. The transistor is biased “on” by the function port output with the +V supplying the current necessary to
activate the relay. The transistor rating will determine the value of the series resistor used between the function port
output and the base of the transistor.
Reverse Bias diode:
In the example shown, the transistor switches to provide a path for current flow through the coil. When the current flow is
interrupted by removing the bias from the base of the transistor, a reverse voltage may be created. The reverse bias diode protect
the coil of the relay.
+5V
INPUT
Ex. Foot SW
typically
50kohm
Microprocessor-side
OUTPUT
Microprocessor-side
+V
1k – 10kohm
Reverse Bias Diode
1k – 10kohm
