Showing posts with label off. Show all posts
Showing posts with label off. Show all posts
Tuesday, October 14, 2014
Latching Relay On Off Switch Circuit
The ambit beneath switches AC or DC ability to a amount application an ultra low ability 3v latching broadcast with two coils. The broadcast can handle about 10 amps of current, up to 250vac. Anniversary time the baby pushbutton is pressed, the ambit either latches the broadcast contacts bankrupt or alleviate them open. The 3v powered ambit uses a distinct 74HC14. This accessory contains six Schmitt activate inverters in the one 14 pin package. Two inverters anatomy a flip/flop circuit.
Anniversary time the pushbutton is pressed, the ambit changes accompaniment and stays in that accompaniment until the button is apprenticed again. With anniversary accompaniment change, a 25ms latching or unlatching beating is produced and is baffled to the actual broadcast coil. The braid attrition is about 45 ohms so about 70ma of accepted is fatigued from the 3v array for anniversary broadcast pulse. The boilerplate ability is so low that the ambit can accomplish for abounding years on one set of batteries. I would advance application two AA or AAA acrid cells.
Thursday, August 28, 2014
Simple On off Inverters Wiring diagram Schematic
This is a Simple On-off Inverters switch Circuit Diagram. Each time the switch closes, the voltage on Cl causes inverter A to change state, with positive feedback from inverter B. Resistor Rl delays the charging and discharging of Cl, making the schema virtually immune to contact bounce. The schema works with either CMOS or TTL gates. The values of R1 and C1 are not critical and can be increased for greater contact bounce protection, if needed. Recommended ranges are 10 K to 1 MO for Rl, and 0.01 to 1.0 p.F for Cl.
Simple On-off Inverters Circuit Diagram
Saturday, August 9, 2014
Auto Turn Off Battery Charger Wiring diagram Schematic
This Auto Turn-Off Battery Charger Circuit Diagram for series-connected 4-cell AA batteries automatically disconnects from mains to stop charging when the batteries are fully charged. It can be used to charge partially discharged cells as well. The schema is simple and can be divided into AC-to-DC converter, relay driver and charging sections. In the AC-to-DC converter section, transformer X1 steps down mains 230V AC to 9V AC at 750 mA, which is rectified by a full-wave rectifier comprising diodes D1 through D4 and filtered by capacitor C1. Regulator IC LM317 (IC1) provides the required 12V DC charging voltage.
Auto Turn-Off Battery Charger Circuit Diagram
When you press switch S1 momentarily, the charger starts operating and the power-on LED1 glows to indicate that the charger is ‘on.’ The relay driver section uses pnp transistors T1, T2 and T3 (each BC558) to energise electromagnetic relay RL1. Relay RL1 is connected to the collector of transistor T1. Transistor T1 is driven by pnp transistor T2, which, in turn, is driven by pnp transistor T3. Resistor R4 (10-ohm, 0.5W) is connected between the emitter and base of transistor T3.
When a current of over 65 mA flows through the 12V line, it causes a voltage drop of about 650 mV across resistor R4 to drive transistor T3 and cut off transistor T2. This, in turn, turns transistor T1 ‘on’ to energise relay RL1.
Now even if the pushbutton is released, mains is still available to the primary of the transformer through its normally open (N/O) contacts. In the charging section, regulator IC1 is biased to give about 7.35V. Preset VR1 is used for adjusting the bias voltage. Diode D6 connected between the output of IC1 and battery limits the output voltage to about 6.7V, which is used for charging the battery. Pushing switch S1 latches relay RL1 and the battery cells start charging. As the voltage per cell increases beyond 1.3V, the voltage drop across resistor R4 starts decreasing. When it falls below 650 mV, transistor T3 cuts off to drive transistor T2 and, in turn, cuts off transistor T3.
As a result, relay RL1 de-energises to cut off the charger and red LED1 turns off. You may determine the charging voltage depending on the NiCd cell specifications by the manufacturer. Here, we’ve set the charging voltage at 7.35V for four 1.5V cells. Nowadays, 700mAH cells are available in the market, which can be charged at 70 mA for 10 hours. The open-schema voltage is about 1.3V. The shut-off voltage point is determined by charging the four cells fully (at 70 mA for 14 hours). After measuring the output voltage, add the diode drop (about 0.65V) and bias LM317 accordingly.
Auto Turn-Off Battery Charger Circuit Diagram
When you press switch S1 momentarily, the charger starts operating and the power-on LED1 glows to indicate that the charger is ‘on.’ The relay driver section uses pnp transistors T1, T2 and T3 (each BC558) to energise electromagnetic relay RL1. Relay RL1 is connected to the collector of transistor T1. Transistor T1 is driven by pnp transistor T2, which, in turn, is driven by pnp transistor T3. Resistor R4 (10-ohm, 0.5W) is connected between the emitter and base of transistor T3.
When a current of over 65 mA flows through the 12V line, it causes a voltage drop of about 650 mV across resistor R4 to drive transistor T3 and cut off transistor T2. This, in turn, turns transistor T1 ‘on’ to energise relay RL1.
Now even if the pushbutton is released, mains is still available to the primary of the transformer through its normally open (N/O) contacts. In the charging section, regulator IC1 is biased to give about 7.35V. Preset VR1 is used for adjusting the bias voltage. Diode D6 connected between the output of IC1 and battery limits the output voltage to about 6.7V, which is used for charging the battery. Pushing switch S1 latches relay RL1 and the battery cells start charging. As the voltage per cell increases beyond 1.3V, the voltage drop across resistor R4 starts decreasing. When it falls below 650 mV, transistor T3 cuts off to drive transistor T2 and, in turn, cuts off transistor T3.
As a result, relay RL1 de-energises to cut off the charger and red LED1 turns off. You may determine the charging voltage depending on the NiCd cell specifications by the manufacturer. Here, we’ve set the charging voltage at 7.35V for four 1.5V cells. Nowadays, 700mAH cells are available in the market, which can be charged at 70 mA for 10 hours. The open-schema voltage is about 1.3V. The shut-off voltage point is determined by charging the four cells fully (at 70 mA for 14 hours). After measuring the output voltage, add the diode drop (about 0.65V) and bias LM317 accordingly.
Author : Y.M. Anandavardhana
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