automatic ഫാന്‍ കണ്ട്രോളര്‍

 automatic ഫാന്‍ കണ്ട്രോളര്‍
താപ നിലയ്ക്കനുസരണമായി  ഒരു ഫാന്‍ ഓണ്‍ -ഓഫ് ചെയ്യേണ്ടതായി വരുമ്പോള്‍ വളരെ പ്രയോജനം ചെയ്യുന്ന സര്‍ക്യൂട്ടാണ്  താഴെ കൊടുത്തിരിക്കുന്നത് .ഉദാഹരണം മുട്ട വിരിയിക്കാനുപയോഗിക്കുന്ന ഇങ്കുബേറ്റര്‍.ബോക്സിലെ താപനില നമ്മള്‍ സെറ്റുചെയ്തിരിക്കുന്നതിലും ഉയരുമ്പോള്‍ (ഇതു പി-1 ഉപയോഗിച്ച് സെറ്റ് ചെയ്യാം) Th 1 (തെര്‍മിസ്റ്റര്‍ ) അതു സെന്‍സ് ചെയ്യുകയും റിലെ ഓണായി അതിനോടനുബന്ധിച്ച് കണക്റ്റ് ചെയ്തിരിക്കുന്ന ഫാനിനെ പ്രവര്‍ത്തിപ്പിച്ച് ഇങ്കുബേറ്റര്‍ ബോക്സിലെ ചൂടു വായുവിനെ പുറത്തേക്ക് കളയുകയും ചെയ്യും.ഇത് പോലെ നിരവധി ഉപയോഗങ്ങല്‍ ഈ സര്‍ക്യൂട്ടിനു കണ്ടുപിടിക്കാം.

Th1, the 50K thermistor, is a standard type. Mine was a bar or rectangular looking thingy. Available from Tandy/Radio-Shack. Almost any type will do. I experimented with different models from 22K to 100K
and all worked fine after replacing the trimmer pot. The one used in the above circuit diagram was a 50K model. This 50K was measured at exactly 25 °C and with 10% tolerance. The resistance increases as the surrounding temperature decreases. Tolerance for my application (cooling a large powersupply coolrib) is 10%. Another name for this thing is 'NTC'. NTC stands for "Negative Temperature Coefficient" which means when the surrounding temperature decreases the resistance of this thermistor will increase. I replaced my thermistor for a 60K hermetically
sealed glass type since the environment for my application may contain corrosive particles which may affect performance on a future date. P1 is a regular Bourns trimmer and adjusts a wide range of temperatures for this circuit.

I used the 10-turn type for a bit finer adjustment but the regular type will work for your application.
R1 is a 'security' resistor just in case the trimmer pot P1 is adjusted all the way to '0' ohms. At which time the thermistor would get the full 12 volt and it will get so hot that it puts blisters on your fingers... :-)R3 feeds a bit of hysteresis back into the op-amp to eliminate relay 'chatter' when the temperature of the thermistor reaches its threshold point. Depending on your application and the type you use for Q1 and Re1, start with 330K or so and adjust its value downwards until your satisfied. The value of 150K shown in the diagram worked for me. Decreasing the value of R2 means more hysteresis, just don't use more then necessary. Or temporarily use a trimmer pot and read off the value. 120K worked for me.

Transistor Q1 can be a 2N2222(A), BC 548,BC 547, etc. Not critical at all. It acts only as a switch for the relay so almost any type will work, as long as it can provide the current needed to activate the relay's coil. D1, the 1N4148, acts as a spark arrestor when the contacts of the relay open and eliminates false triggering. For my application the 1N4148 was good enough since the tiny relay I used was only 1 amp.

However, you can use a large variety of diodes here, my next choice would be a regular purpose 1N4001 or something and should be used if your relay type can handle more then 1 amp. If you like to make your own pcb, try the one above. The pcb is fitted with holes for the relay but may not fit your particular relay. It was designed for a Aromat HB1-DC12V type.

The variety and model of relays is just to great. How to mount it then? Well, I left ample space on the pcb to mount your relay. You can even mount it up-side-down and connect the wires individually. Use Silicon glue, cyanoacrylate ester (crazy glue), or double-sided tape to hold the relay in place. Works well. Note that the pcb and layout is not according to the circuit diagram in regards to the hookup of the fans. The PCB measures approximately 1.5 x 3 inches (4.8 x 7.6mm) If you print the pcb to an inkjet printer it is probably not to scale. Try to fit a 8-pin ic socket on the printed copy to make sure it fits before making the pcb...

ക്രിസ്തുമസ് ലൈറ്റ് ഡെക്കറേഷന്‍

ക്രിസ്തുമസ് ലൈറ്റ് ഡെക്കറേഷന്‍
This project flashes 18 LEDs at three different rates and you can use these to create a Christmas decoration of your choice. The circuit is kept simple (and cheap!) by using the 4060B IC which is a counter and oscillator (clock) in one package. The circuit requires a 9V supply, such as a PP3 battery. It will not work with lower voltages and a higher voltage will destroy the LEDs.
The preset variable resistor can be used to adjust the oscillator frequency and this determines the flash rate of the LEDs. The IC limits the current to and from its outputs so the LEDs can be safely connected without resistors in series to limit the current. The stripboard part of the circuit is easy to build but the wiring for the LEDs needs care so detailed instructions are provided below.
You can design your own decoration or download our Christmas Tree template to print out and glue onto thick card, hardboard etc. The template has two tree outlines on one sheet of A4 paper.


Warning!
Using a battery (or power supply) with a voltage higher than 9V will destroy the LEDs.
You can see from the circuit diagram (below) that 6 LEDs are connected in series between the +9V supply and 0V. Each LED requires about 2V across it to light, so using a voltage of about 12V (= 6 × 2V) or more will make the LEDs conduct directly, regardless of the 4060B IC. With no series resistor to limit the current this will destroy the LEDs.
 

Parts Required

• resistors: 10k, 470k
• preset: 47k (this could be 100k if necessary)
• capacitor: 0.1µF
• 4060B IC
• 16-pin DIL socket for IC
• LEDs × 18, 5mm diameter, any mix of colours: red, orange, amber, yellow or green
• on/off switch
• battery clip for 9V PP3
• stripboard 13 rows × 18 holes 
•  
  
  

  Building the Circuit

• Begin by soldering the components onto the stripboard as shown in the diagram above. Do not insert the 4060B IC at this stage.

Arranging the LEDs:

2. Cut out a suitable shape from stiff card (or similar material), such as our Christmas Tree template. Paint or colour the card at this stage if necessary.
3. Plan the layout of the 18 LEDs (suggested positions are marked on our template).
4. Drill 5mm holes for the LEDs - put the card on a piece of scrap wood to do this without damaging the card or the table.
5. Push LEDs into the holes, they should be a fairly tight fit and glue should not be necessary.
6. Label the LEDs D1 - D18 at random on the back of the card.

Wiring of the LEDs: Use stranded wire for all the connections to the LEDs and solder all wires near to the LED body so the leads can be trimmed short later on.
The wire colours are suggested to avoid confusion but you can use other colours if you wish, the electricity won't mind! For example you could use red and black as suggested but substitute yellow and white for the blue and green suggested.

7. Cut all the LED short leads to be very short to make identification easier:
8. Connect RED wire to link up all the LONG leads of D1, D2 and D3.
   Remember to solder wires near to the LED body so the long lead can be trimmed short later on.
9. Connect BLACK wire to link up all the SHORT leads of D16, D17 and D18.
10. Use 3 pieces of BLUE wire to connect:
    • D7 short - D10 long
    • D8 short - D11 long
    • D9 short - D12 long
11. Use 12 pieces of GREEN wire to connect:
    • D1 short - D4 long
    • D4 short - D7 long
    • D2 short - D5 long
    • D5 short - D8 long
    • D3 short - D6 long
    • D6 short - D9 long
    • D10 short - D13 long
    • D13 short - D16 long
    • D11 short - D14 long
    • D14 short - D17 long
    • D12 short - D15 long
    • D15 short - D18 long
12. Connect the RED wire from the circuit board to the RED wiring on the decoration (connect it to any convenient point).
13. Connect the BLACK wire from the circuit board to the BLACK wiring on the decoration (connect it to any convenient point).
14. Connect the 3 BLUE wires from the circuit board to each of the 3 BLUE wires on the decoration, they may be connected in any order.
15. Carefully check all wiring.
16. Trim the long LED leads.
17. Plug the 4060B into its holder.
18. Connect a 9V battery and switch on.
19. Using a small screwdriver, adjust the 47k preset variable resistor to give a suitable flash rate for the LEDs. 
20.  

    
    

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    Circuit diagram

    

    Stripboard Layout