Super Tone Control for Car Audio.

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1. LF353


When the amplifier is installed abaft in the suitcase, we shall charge a about-face works stop. The LA47536 possesses a action angle by in it pin4. This ache crave a baby astriction above to 2V in alpha up the amplifier. Transistor Q1 and Q2 makes the action of walking stop for distance. Back the disciplinarian activates the larboard indicator, either ablaze the aback fires or columnist on the anchor , lamps rear burn active Q2 who he alike fabricated to drive Q1 who applies a astriction > 2V on it pin4.

Fire Alarm Circuit Using LDR

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Download datasheet semiconductor component. (PDF Format)

1. LM7805

2. IN4007

3. BC107

4. UM66

5. TDA2002

Here is a simple fire alarm circuit based on a LDR and lamp pair for sensing the fire.The alarm works by sensing the smoke produced during fire.The circuit produces an audible alarm when the fire breaks out with smoke.

When there is no smoke the light from the bulb will be directly falling on the LDR.The LDR resistance will be low and so the voltage across it (below .6V).The transistor will be OFF and nothing happens.When there is sufficient smoke to mask the light from falling on LDR, the LDR resistance increases and so do the voltage across it.Now the transistor will switch to ON.This gives power to the IC1 and it outputs 5V.This powers the tone generator IC UM66 (IC2) to play a music.This music will be amplified by IC3 (TDA 2002) to drive the speaker.

The diode D1 and D2 in combination drops 1.4 V to give the rated voltage (3.5V ) to UM66 .UM 66 cannot withstand more than 4V.
* The speaker can be a 8Ω tweeter.
* POT R4 can be used to adjust the sensitivity of the alarm.
* POT R3 can be used for varying the volume of the alarm.
* Any general purpose NPN transistor(like BC548,BC148,2N222) can be used for Q1.
* The circuit can be powered from a 9V battery or a 9V DC power supply.
* Instead of bulb you can use a bright LED with a 1K resistor series to it.

Switch Mode Pre-Regulator

The botheration was that a voltage regulator had to bead the 18 volt capital ability accumulation voltage to 8 volts at 500ma to ability the CD player, crumbling 5 watts of ability and causing a lot of calefaction central the bunched unit. This ambit acts as an interference-free pre-regulator to abundantly abate the ability loss..

The achievement voltage of this ambit is artless by ability band fluctuations. Amount voltage aberration is alone abased on the on-resistance of Q2 and the amount of C2 (re: ripple). The achievement voltage can be set so that the ripple lulls are aloof aloft the drop-out voltage of the beeline regulator at best amount for best activity conservation. The college amount you aces for C2, the added activity you can save and the added abiding the pre-regulator’s achievement voltage.

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Datasheet semiconductor component. (PDF Format)

1. 2SK2314
2. 2N3904
3. IN4004
4. IN4744
5. IN4148
6. IN5231

LM78XX Positive Regulators Universal PCB for PSU

The 78XX family is ideally suited for this job, and with this little PCB you can easily build small Power Supplies for virtually every application.

The circuit is very simple:

The Alternating current is applied to X1 and rectifies by B1.

It charges a large Capacitor C1 to power the regulator.

The output voltage depends on the Regulator you use, e.g. 7805, 7812,7815…

Dimensionierung:

C1:4700u, with sufficient voltage Rating!

C2:0.33u

C3:0.1u

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Datasheet semiconductor download. (PDF Format)

1. LM78XX