NE 555 & LM 567 Remote Control Circuit

Remote control circuit consists of two parts, one is transmitter and the other is receiver. A simple diagram is schematic remote control. The transmitter circuit’s transmitter IC is controlled by NE555. Receiver circuit works by the signal emitted frequency which is emitted by that transmitter circuit. Transmitted signal frequency must be equal to the frequency decoder of the receiver circuit. The NE 555 generated frequency is same that receive frequency of IC LM 567. 

The output frequency of the transmitter circuit is f,

f = 1.44/(Ra+2Rb)C

 

           The resistor R1 is a receiver variable to facilitate the process of tuning. The system works well when the circuit is ready. The first step is tuning by way of the transmitter is turned on continuously, while the receiver R1 to set the value to be able to detect the signal transmitter. The second part is the receiver is controlled by LM 567. The following is a schematic drawing recipient.

f = 1 / (1.1 xR1xC1)

This frequency depends on the value of R₁ and C₁.

In the picture on top of each channel is designed with a different frequency. By considering the bandwidth of the frequency detection signal LM 567, inter-frequency channels should have a big enough difference, let’s try with a difference of 5 KHz.

 

[source:hobbyelectron.blogspot.com]

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LM56 Thermostat Project Circuit Diagram

LM56 Thermostat Project Circuit

This electronic circuit thermostat using IC LM56 diagram which simple project you can use as reference guide. As you know, IC LM56 is especially accurate dual output low power thermostat characterize by National Semiconductors. 2 stable temperature trip points called VT1 and VT2 are made with dividing the IC LM56 1.250Volt internal voltage reference by three external resistors (R1, R2 and R3) component. There are 2 digital outputs for IC LM56 that is Output1 becomes LOW when the temperature increases above T1 and goes HIGH when the temperature decreases below (T1±Hysteresis Temperature). Component IC LM56 has a variety of useful features such as internal temperature sensor, 2 internal voltage comparators, internal voltage reference etc.

The circuit diagram thermostat using IC LM56 values of R1, R2 and R3 for the required trip points VT1 and VT2 can be determined using the subsequent equations.

VT1 = 1.250V x (R1)/ (R1 + R2 + R3)
VT2 = 1.250V x (R1 + R2)/ (R1 + R2 + R3)
where:
(R1 + R2 + R3) = 27 k Ohms and
VT1 or T2 = [6.20 mV/degree Celsius x T] = 395 mV therefore:
R1 = VT1/ (1.25V) x 27 k Ohms
R2 = (VT2/ (1.25V) x 27 k Ohms) – R1
R3 = 27 k Ohms – R1 – R2

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LM35 Smart Heater Controller Project

LM35 Smart Heater Controller Schematic

Minuscule circuit of the electronic heater controller presented here is built around the renowned 3-Pin Integrated Temperature Sensor LM35 (IC1) from NSC. Besides, a popular BiMos Op-amp CA3140 (IC2) is used to sense the status of the temperature sensor IC1, which also controls a solid-state switch formed by a high power Triac BT136(T1). Resistive type electric heater at the output of T1 turns to ON and to OFF states as instructed by the control circuit. This gadget can be used as an efficient and safe heater in living rooms, incubators, heavy electric/electronic instrument etc.

Normally, when the temperature is below a set value (Decided by multi-turn preset pot P1), voltage at the inverting input (pin2) of IC1 is lower than the level at the non-inverting terminal (pin3). So, the comparator output (at pin 6) of IC1 goes high and T1 is triggered to supply mains power to the desired heater element.

When the temperature increases above the set value, say 50-60 degree centigrade, the inverting pin of IC1 also goes above the non-inverting pin and hence the comparator output falls. This stops triggering of T1 preventing the mains supply from reaching the heater element. Forunately, the threshold value is user-controllable and can be set anywhere between 0 to 100 Degree centigrade.

The circuit works off stable 9Volt dc supply, which may be derived from the mains supply using a standard ac mains adaptor (100mA at 9V) or using a traditional capacitive voltage divider assembly. You can find such power circuits elsewhere in this website.

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