There are several methods used to 'listen in' to a room. A popular method is to fit a microphone in the area, e.g. in the ceiling or another convenient place in the room and run wires back to the LP, (listening post) at a convenient place in the building.
It is not possible to just fit a microphone and run a length of cable back to the listening post, the signal from the microphone will be reduced and become noisy if the cable is too long. A special amplifier is connected to the microphone allowing a long length of cable to be used back to the listening post.
Normally, such systems need to have four wires, two for power and two to carry the audio signal.
Our audio room monitor only needs two wires which carry the audio from the microphone amplifier back to the listening post, and also carry power back to the microphone.
This system is known as the TWO-WIRE room listener.

Another popular method of listening into a room, is to use a special module connected across the telephone line in the room to be monitored. After fitting this module across the phone line, all room conversations can be listened to by connecting the main amplifier across the phone line at some other place.

TWO WIRE ROOM MODULE (TWM) This is the module with attached microphone to be fitted in the room to be listened to.

TAPE COPYING ADAPTOR

Whilst a duplicate copy of a tape is often needed, e.g. a duplicate tape of telephone conversations, it is not possible to copy a tape by simply connecting the headphone output of one tape deck to the microphone input of another recorder.

It is possible to duplicate a tape using two standard cassette recorders after fitting the COPYING ADAPTOR between the headphone output of one machine and the mic input of another.
A headphone socket on the copying adaptor allows you to listen to the tape whilst making the copy.

RADIO TRANSMITTERS (BUGS)

A 'BUG' is a radio transmitter that can be left in a room allowing the user to listen into room conversations by tuning into the 'bug' with a radio receiver. This bug can be received on a normal fm radio.
Line of sight range is about 400m, and battery life is around 48hours. FM BUG, - RT1

For secure 'bugging', it is not advisable to use transmitters that can be picked up with a normal fm radio.
For more 'professional' applications a bug with a matching radio receiver is used.

THE TX33/UX33 is a transmitter and receiver combination operating outside the normal fm radio band. The receiver and transmitter operate on a fixed frequency, no tuning is necessary as the receiver is matched to the transmitter, i.e. the TX33 can only be received by using the UX33 receiver.
Line of sight range is 150-200m.
UHF BUG, -TX33/UX33 Transmitter/Receiver pair

THE TR33/UR33 WIRELESS RECORDER is also a telephone transmitter system, but the receiver is built inside a tape recorder, making it simpler to use.
The transmitter is attached to the line and the recorder is placed within range. The recorder is put onto record but will only start recording when the phone is used, and switch off automatically when the phone is put down.
TR33/UR33 SYSTEM

Two-Wire module which is installed in room to be listened into and two-wire amplifier which is used in area to listen in

This unique system uses only two wires to carry the sound from the microphone module in the room to the listening post and the same two wires carry the power back to the microphone module

Two output jacks (headphones/recording) Powered by a 9V battery

The receiver has 3 channels (A, B, C)

Used to receive signals from either the credit card, 220 V, telephone, pen and room transmitters

The distance ranges from 100 m to 1 km depending on the transmitter

UHF Pen Transmitter

Distance : 150m
Battery life : 12 hours
Battery required : 2x watch battery
Size : 130mm long

UHF Long Range Room Transmitter

Distance : 1km
Battery life :60 hours
Battery required : 9 volt battery
Size : 69x20x19mm (incl battery)

UHF Med Range Room Transmitter

Distance : 400m
Battery life : 5 days
Battery required : 2x n size batteries
Size : 69x22x22mm (incl battery)

UHF 220v Mains Transmitter

Distance : 150m
Battery : no battery as it works on 220v mains
Size : 44x12x12mm

UHF Credit Card Transmitter

Distance : 150m
Battery life : 60 hours on normal
Battery life on vox : 3-5 days
Battery : CR 2430
Size : 85x53x4.5mm

UHF Telephone Transmitter

Distance : 150m
No battery required
Size : 22x12x12mm

We've just landed a shipment of this brand-new product, which is certain to create great interest amongst your customers.

These ultra-compact, stylishly designed walkie-talkies are ideal for dozens of applications

FEATURES:
8 Channels
PTT or VOX control
Frequency scanning
Dual frequency watch

Supplied complete with handsfree headsets, rechargeable batteries, and a wall charger.

Typical range is around 1km LOS.
NO LICENCE NEEDED!