Featured Post

High CMRR Instrumentation Amplifier (Schematic and Layout) design for biomedical applications

on
Instrumentation amplifiers are intended to be used whenever acquisition of a useful signal is difficult. IA’s must have extremely high input impedances because source impedances may be high and/or unbalanced. bias and offset currents are low and relatively stable so that the source impedance need not be constant. Balanced differential inputs are provided so that the signal source may be referenced to any reasonable level independent of the IA output load reference. Common mode rejection, a measure of input balance, is very high so that noise pickup and ground drops, characteristic of remote sensor applications, are minimized.Care is taken to provide high, well characterized stability of critical parameters under varying conditions, such as changing temperatures and supply voltages. Finally, all components that are critical to the performance of the IA are internal to the device. The precision of an IA is provided at the expense of flexibility. By committing to the one specific task of
2

Red Alert Str trek Alarm Siren

on 
Parts List:
R1,R4 = 10K                          C1 = 10uF/25V, electrolytic
   R2 = 75K                    C2,C3,C4 = 0.01uF (10nF), ceramic
   R3 = 1K                           C5 = 470uF/25V, electrolytic
   R5 = 100K                    IC1,IC2 = 555 Timer/Oscillator
   Q1 = 2N3055                 D1,D3,D4 = 1N4001
   LS = Loudspeaker, 8 ohm           D2 = 1N4148


Notes:
The circuit above provides a 'pulse-tone', like the one you know from the old Star Trek. The output stage contains a power-booster with Q1 (2N3055), providing several watts to the loudspeaker SPKR1.
Clamping diodes are used to limit the speaker's inductive kickback to a safe level. To prevent the output signal from feeding back into the 555's via the supply line, the supply lines are filtered by a capacitor and an isolating diode (C5 and D2).
This circuit acts as a pulsed-tone alarm-call generator. Integrated circuit U1 acts as an 800-Hz tone generator, and is gated on and off once per second by U2 via D1.

Comments

Post a Comment