User guide

! 1. Connect the battery to the battery snap.

! 2. Set the voltmeter to read 20VAC and connect

the COM lead to the negative (–) side of the

battery and the V lead to pad of pin 8 of IC U3

as shown in Figure 5. The meter should

indicate 0V. Push switch SW1. The meter

should indicate 3-5VAC.

If not:

a) Check U5 and C3 to be sure that they

are installed as shown in the assembly

instructions.

b) Check R13 and R14 are the correct

values.

Remove the battery from the battery snap and

the leads from the tester.

-9-

SECTION B - OSCILLATOR

The oscillator section consists of a 555 timing

circuit, resistors R13, R14, and capacitor C3. The

555 IC is configured as an astable or free-running

oscillator. The values of the resistor R14 and

capacitor C3 set the output frequency at 8Hz. The

IC will produce a continuous 8Hz square wave from

pin 3 as long as it is powered.

TESTING

Figure 4

To Switches

Figure 5

COM

VAC