DoorKing Circuit Board

The circuit board above has a number of functions.

• The board has a power supply area where 28 VAC is converted to 5 VDC for the TTL circuitry and voltages for other functions, like the MODEM.
• It has a built in MODEM (modulate/demodulate) to transfer data across a leased telephone line to the board.
• There is a ROM (read only memory) to hold all of the residents names and phone numbers, even if the board loses power.
• There is a moving display with a programmable message and may display the residents names.
• There are relays to open and close gates.
• The board has a DTMF decoder. It means dual tone – multiple frequency. When you press a number on any telephone keypad, it generates two simultaneous tones.
• A microphone and speaker are used to speak to the homeowner. When the homeowner wishes to open the gate for the person at the entry, they press the number 9 key on their telephone for this board to open the gate.
• Some boards may have a card reader for the residents. Newer boards have even more security devices available, but at some point one has to decide when enough is enough. A swinging gate can only achieve so much security. Our gates weigh hundreds of pounds, swings slowly, and if someone wants to, they can easily tailgate another vehicle.

Repairing an electric gate can be a difficult process. One could write a book on the procedures for all of the different makes and models. I found the best source for me is the manufacture’s website. Gate openers range from ones that are relatively simple, that just open from a wireless signal (handheld clicker) or keypad, to complicated ones like the one shown above.