Velleman projects K2604 Assembly instructions - Manual (Page 5)

5
construction
T1 : BD681
8. Transistor
IC1 : LM324
9. IC. Watch the position of the notch!
1. Place all 3 trimmers in their mid-position.
2. Connect a push-button or switch to the "PB" contacts.
3. Connect a loudspeaker (4-16ohm) to the points "LS".
4. Connect a power supply (8-14VDC) to the points "VDC", check for
the correct polarity!
5. Press the button or switch to start.
6. Trim RV1, RV2 and RV3 to obtain the desired effect. The positive
and the negative sweep (modulation) are adjusted respectively with
RV1 and RV2. Trimmer RV3 adjust the frequency.
TIP: use a 4ohm/5W resistor for R8 and a loudspeaker of 3-5W
to obtain a louder siren.
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