Wiring circuit

Tuesday, September 16, 2014

AC Line Current Detector Wiring diagram Schematic

This schema diagram will detect AC line currents of about 250 mA or more without making any electrical connections to the line. Current is detected by passing one of the AC lines through an inductive pickup (L1) made with a 1 inch diameter U-bolt wound with 800 turns of #30 - #35 magnet wire. The pickup could be made from other iron type rings or transformer cores that allows enough space to pass one of the AC lines through the center.

Only one of the current carrying lines, either the line or the neutral should be put through the center of the pickup to avoid the fields cancelling. I tested the schema using a 2 wire extension cord which I had separated the twin wires a small distance with an exacto knife to allow the U-bolt to encircle only one wire.

AC Line Current Detector Circuit Diagram

The magnetic pickup (U-bolt) produces about 4 millivolts peak for a AC line current of 250 mA, or AC load of around 30 watts. The signal from the pickup is raised about 200 times at the output of the op-amp pin 1 which is then peak detected by the capacitor and diode connected to pin 1. The second op-amp is used as a comparator which detects a voltage rise greater than the diode drop. The minimum signal needed to cause the comparator stage output to switch positive is around 800 mV peak which corresponds to about a 30 watt load on the AC line.

The output 1458 op-amp will only swing within a couple volts of ground so a voltage divider (1K/470) is used to reduce the no-signal voltage to about 0.7 volts. An additional diode is added in series with the transistor base to ensure it turns off when the op-amp voltage is 2 volts. You may get a little bit of relay chatter if the AC load is close to the switching point so a larger load of 50 watts or more is recommended. The sensitivity could be increased by adding more turns to the pickup.

Tuesday, September 9, 2014

Live line Detector

If the unit is brought close to a live conductor (insulated, and even buried in plaster) capacitive coupling between the live conductor and the probe clocks the counter, and causes the LED to flash 5 times per second, because the 4017 IC divides the mains 50Hz frequency by 10.When remote from a live line, the unit stops counting, the LED resulting permanently off.

Live-line

Parts:
C1____________100nF 63V Polyester or Ceramic Capacitor D1_____________Red LED (any type) IC1____________4017 Decade counter with 10 decoded outputs IC P1_____________SPST Pushbutton B1_____________3V Battery (two 1.5V AA or AAA cells in series etc.) Sensing probe__3 to 15 cm. long, stiff insulated piece of wire Notes: * Sensitivity can be varied using a more or less long sensing probe. * Due to 3V operation, the LEDs current limiting resistor can be omitted.

Friday, September 5, 2014

Simple Electromagnetic Field Detector Schematic

This schema is sensitive to low frequency electromagnetic radiation and will detect for example hidden wiring or the field that encompasses a transformer. Pickup is by a radial type inductor, used as a probe which responds well to low frequency changing magnetic and electric fields. Ordinary headphones are used to for detection. The field that surrounds a transformer is heard as a 50 or 60Hz buzz. The schema is below:-

Electromagnetic Field Detector Circuit Diagram

Notes:

I threaded a length of screened cable through an old pen tube and soldered the ends to a radial type can inductor. I used 1mH. The inductor fitted snugly into the pen tube. The opposite end of the cable connects to the input of the op-amp. Any op-amp should work here, possibly better results may be achieved with a low noise FET type such as the LF351. The 2M2 potentiometer acts as a gain control and the output is a pair of headphones. Stereo types can be used if they are wired as mono. I used an 8 ohm type, but the schema should work equally well with higher impedance types. The probe (shown below) may be connected via screened cable and a 3.5mm stereo plug and socket.

Detection:

The sensitivity of this schema is good. Mains wiring buried an inch in plaster can be detected with precision. A small load on the electric supply is all that is needed; a 20 watt desk lamp or similar will suffice. The hum field surrounding a transformer can be detected oat over 7 inches. Domestic appliances such as videos and alarm clocks all produce interference which can be heard with the probe. The electric field surrounding a loudspeaker or earpiece can also be heard. Try lifting a telephone and place the probe near the earpiece. A telephone pickup coil can be used in place of the inductor if desired. I will make an improved version of this schema with a meter output later.

Monday, September 1, 2014

Simple Audio Peak Detector

This audio peak detector allows a pair of stereo channels to be monitored on a sin-gle LED. Identical schemary is used in the left and right channels. Use is made of the switch-ing levels of Schmitt trigger NAND gates inside the familiar 4093 IC. The threshold level for gate IC1.A (IC1.B) is set with the aid of preset P1, which supplies a high-impedance bias level via R2 (R1).

Simple Audio Peak Detector Circuit diagram :

Simple Audio Peak Detector Circuit Diagram

When, owing to the instantaneous level of the audio signal superimposed on the bias voltage by C3 (C2), the dc level at pins 1 and 2 (5 and 6) of the Schmitt trigger gate drops below a certain level, the output of IC1.A (IC1.B) will go High. This level is copied to the input of IC1.C via D2 (D1) and due to the inverting action of IC1.C, LED D3 will light. Network R3-C1 provides some delay to enable very short audio peaks to be reliably indicated. Initially turn the wiper of P1 to the +12 V extreme — LED D3 should remain out.

Then apply ‘line’ level audio to K1 and K3, preferably music with lots of peaks (for example, drum ‘n bass). Carefully adjust P1 until the peaks in the music are indicated by D3. The schema has double RCA connectors for the left and right channels to obviate the use of those rare and expensive audio splitter (‘Y’) cables.

Author : Flemming Jensen – Copyright : Elektor Electronic

Sunday, August 31, 2014

Simple Rain Alarm or Water Detector Circuit with SCR 106CY

Rain detector schema Diagram

Rain detector schema can be applied to the project or any other hobby, which is so simple principles.When it rains plate (sensor) will receive rain. And a dedicated work has paid to SCR1 and flow control Buzzer noise.

Electronic Part List

R1 1K 1/4 W Resistor
R2 680 Ohm 1/4 W Resistor
D1 1N4001 Silicon Diode
BZ1 12V Buzzer
S1 SPST Switch
SCR1 C106B1 SCR 106CY
SENSOR See

Notes

The sensor is a small piece of PC board etched to the pattern showen in the schematic. The traces should be very close to each other, but never touching. A large spiral pattern would also work. 2. Make sure to use a loud buzzer