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Daviscomms Br802



ProOne+

An obsolete pager can be converted into a single channel receiver for paging monitoring by adding a discriminator output.

The Daviscomms Br 802 contains a single chip paging receiver IC: the TA31149. The pins on this IC are separated only 0.65 mm. However, soldering to the IC is not necessary if you follow the instructions below.

Be advised that the receiver IC has a built-in 2 level slicer. This modification only works for 2-level paging.

Daviscomms Br802 (ProOne+ in the Netherlands)

Each pager contains a battery saving mechanism. At regular intervals, the receiver is switched on briefly to check if there are messages. If not, the receiver will sleep until the next interval. To be able to use the pager as a monitoring receiver, this battery saving mechanism needs to be sdisabled to open the receiver continuously. Obviously, as a result battery life will decrease considerably.

Important spots
The BS contact is cut off
Three important spots: BS, V+ and Data
The BS pin is cut
Follow the next steps to make a data output on the Br802:
  • Cut the PCB pin under point 'BS' with side cutters. This disables the connection between the microprocessor on the bottom printed circuit board from sending battery saving commands to the receiver
  • Using a piece of insulated wire, connect point 'BS' with point 'V+'. This puts a HI state on pin 17 of the receiver IC, which opens the receiver continuously
  • Connect point 'Data' to point 'V+' using a 1.2 k resistor. 'Data' is connected directly to pin 19 of the receiver IC. This is an open collector output, which makes a pull-up resistor necessary
  • Connect a 10 k resistor to 'Data'.
  • Connect the other pin of the 10 k resistor to the inner conductor of a strand of shielded wire. Connect the shield to ground, close to the battery minus contact.
discriminator output
pigtail
The data output
The pigtail from the back of the pager

As there is not enough clearance for a chassis socket, you can drill a hole and lead the shielded wire outside. You can use a tyrap as strain relief. The shielded wire can be terminated with a female 3.5 mm connector. This 'pigtail' enables using a 2 levelinterface or audio cable.

You can also box the pager and add a 1.5 Volt power supply. You can find a description here.



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