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Cute Temperature Controller – Electronics For You

Remark errors or corrections discovered for this circuit, and get the possibility to win huge!

Fashionable electronics have advanced to a really nice extent as we speak such that it over spreads on the territory of laptop science on one hand whereas beneath spreads on the zone of Data know-how as nicely. At present there may be hardly any digital undertaking which doesn’t use the micro controller unit (MCU) and or the pc programming languages.

Nevertheless, nonetheless there are tasks which might strip down all these excessive tech MCU and laptop packages and might nonetheless make life higher and simpler by exactly doing the identical factor that have been supposed to be achieved utilizing & managed by MCUs & software program.

Temperature controller – TMP36

In our each day life area, temperature controller has umpteen variety of makes use of – rice cooker, fridge, water geyser, micro wave oven, air conditioners all makes use of temperature controller. TMP36 is one such machine which, when related to an MCU with appropriate programming can work as a splendid temperature controller. It exactly measures temperatures ,provides enter to the MCU and the MCU with the assistance of software program, turns the sign into management command for the related units like relays and others. On this undertaking the TMP36 controls the relay in the identical method besides there isn’t a MCU or software program is utilized in between. Merely and instantly it controls the relay utilizing a couple of discrete elements but very exact and easy.


Rules of Operation:

TMP36 has the next traits.

  1. TMP36 has a low voltage operation – 2.7 volt to five.5 volt
  2. 40 Deg Cent to +150 Deg Cent working zone.
  3. Linear operation y = mx + c
  4. Measure temperature instantly into mili voltage. Uniform linearity of 20mV / Deg C
  5. Lower than 50 µA Quiescent Present.
  6. Ramp up = 3 Deg C/ Second and Ramp Down = 6 Deg C / Second.

The principle sensor TMP36 picks up temperature, converts it into millivolt. Which is then measured by the NPN, PNP junction – the Sziklai pair after which when the bottom voltage overcomes the bias restrict the PNP transistor conducts and the 5Volt relay will get energized. NPN-PNP junction (the Sziklai pair ) has a bonus over different Darlington pair is that it’s base-emitter voltage is 0.61 volt not like 1.22 volt for the opposite Darlington pair. Thus making the low voltage operation potential.

Schematic diagram

Fig. 1

Part Record

R1 = 1K
R2 = 10K
R3 = 4.7K multi flip trim pot.

C1 = 250 MFD, 10 Volt.

L1 = 5Volt Relay

IC1 = 7805
IC2 = TMP36
TR1 = BC547
TR2 = SK100
D1 = IN60 Diode

Fig-1 exhibits the schematic of the circuit diagram whereas Fig-2 exhibits a typical TMP36. The entire undertaking has a really small kind issue and may be powered by a small battery of 9- 12 Volt and consumes very small present to run very lengthy.

Fig. 2


That is the place we shed off the cumbersome MCUs and make the circuit easy. The 4.7K trim pot is a exact multi flip sort to set the temperature set level. Warmth up the probe to the specified temperature after which modify the trim pot in order that the relay simply de-energizes. At this level if the temperature will increase past that time the relay will energize once more. The NC (or NO) contact of the relay could also be used to disconnect / reconnect a charger, gadget ,cooker or soldering iron and so on. Conversely when the temperature reduces ,the TMP36 cools down and the relay will get energized once more thus reconnecting the machine as soon as once more.

Oscillation in opposition to a imply temperature

The TMP36 has a ramp up of three Deg C/Second and ramp down of 6 Deg C / Second. So robotically it takes a 3 diploma overlap per second on it’s personal to keep away from oscillation over a imply temperature moreover for a bodily physique the warmth doesn’t dissipate so quick except there may be quick cooling offered.


The place can you employ it

Ni-Mh or Lion batteries: For those who can cease the overcharging of those batteries when the battery reaches a specific temperature (for Ni-Mh it’s 45 Deg C to 50 Deg C ,for Lion & Lipo it’s 45 Deg C) the life of those batteries will lengthen past regular utilization.

Author's Prototype
Fig. 3: Creator’s Prototype

Tip temperature of the soldering iron: Use the NC connection to disconnect the soldering iron provide and put the TMP36 little away from the tip the place temperature is under 150 Deg C.

Modulate the fuel burner when the water begins boiling: use the NO connection to control the shimmer knob/motor and put the TMP36 in direct contact with the boiling liquid – use leak proof metallic defend sort TMP36.



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