Block Diagram; Functional Overview Of Key Circuits; Controls And Indicators; Activation Sense Circuits (5) - Bovie AARON 2250 Service Manual

BLOCK DIAGRAM

Figure 4 – 1 Functional Block Diagram of the Aaron 2250 system.

FUNCTIONAL OVERVIEW OF KEY CIRCUITS

The following descriptions highlight the main circuits in the Aaron 2250.

Controls and Indicators

The front panel overlay contains 10 membrane function switches. Each membrane switch is used to toggle between
modes, presets, and power settings. The overlay interfaces with the display PCB to control user requests.

Activation Sense Circuits (5)

The Activation (Request) Sensing Circuits are used by the control circuit to detect both hand controlled
activation and foot controlled activation requests. These circuits are made up of a Colpitts Oscillator
(operating at approximately 50kHz) and a level detection circuit.
In a non-activation status, the Colpitts Oscillator operates at its set operating frequency, and presents a sine wave to
the level detection circuit. The level detection circuit converts the sine wave into a square wave. Activation will not
occur as long as a square wave is present.
When a resistance (approx. 200 Ω or less) is presented to the transformer's secondary winding by a hand-control or
foot-control, the sense transformer is essentially shorted. The "short" is felt on the transformer's primary winding
causing the Colpitts Oscillator to temporarily shut down.
When the oscillator shuts down, the sense signal becomes +5 VDC (logic "1"). This informs the system that a
handswitch or footswitch activation has been made.
4-2 Aaron Medical