From : http://ourworld.compuserve.com/homepages/Bill_Bowden/ Here’s a power-on time delay relay circuit that takes advantage of the emitter/base breakdown voltage of an ordinary bi-polar transistor. The reverse connected emitter/base junction of a 2N3904 transistor is used as an 8 volt zener diode which creates a higher turn-on voltage for the Darlington connected… Read more »
circuit Regulated Power Supply by Transistor (TIP31) This is simple dc power supply circuit. That use transistor be important equipment perform boost up current give the power goes up. By have the zener diode formed control voltage be stable the character Regulated base. By this circuit can give voltage 9… Read more »
Regulator Booster by transistor This circuit can help enlarge current of power supply circuit that use Ic regulator well. Q1 is BFX88 or Equivalent Q2 is BD132 or Equivalent
This is Two-Down-One circuit. It is Alarm circuit control by SW1. display with Bell electronics. The detail more please see in image.
The circuit will limit the current through the supply wires to 5.5A for about 1.5sec. After that time the relay will close and the current flow won’t be restricted anymore. This is a very interesting circuit if you have a large toroid with big electrolytic caps connected to the power… Read more »
This circuit works with battery 9V a piece is very small. For the work happens independently don’t be under house electricity. The circuit will make a noise to warn work as soon as , detect which be switch model usual close the circuit or aluminium , eliminated separate.
Circuit Two Tone Alarm with IC LM3900 This be Two tone alarm use op-amp IC number LM3900 (Quad Amplifiers) perform produce the frequency square wave 2 level , be high frequency and low then mix the sound in the end danger beep that is appropriate it has can to link… Read more »
Parts: R1,R3____________1K 1/4W Resistors R2,R5___________10K 1/4W Resistors R4_____________220R 1/4W Resistor R6_____________220K 1/4W Resistor R7______________22K 1/4W Resistor R8_____________100K 1/4W Resistor C1,C2___________22ÂµF 25V Electrolytic Capacitors C3______________10nF 63V Polyester or Ceramic Capacitor C4______________47ÂµF 25V Electrolytic Capacitor Q1,Q2_________BC557 45V 100mA PNP Transistors Q3____________BC337 45V 800mA NPN Transistor SW1___________SPST Toggle or Slide Main Switch (See… Read more »
Radio Wave Alarm by Rev. Thomas Scarborough – firstname.lastname@example.org This simple circuit is sure to have the police beating a path to your door – however, it has the added advantage of alerting you to their presence even before their footsteps fall on the doormat. radio wave alarm The circuit… Read more »
Below is the microphone circuit diagram for sound card system. I crack my microphone sound blaster type.