SIMPLE LPG /Butane/Propane gas SENSOR CIRCUIT

                       SIMPLE LPG/Butane/Propane  GAS SENSOR CIRCUIT (TESTED OK)

 If  LPG  used in kitchen is having leakage somewhere,how we come to know ? Since LPG is intentionally  mixed with ethyl mercaptan  for sensing  gas leakage by its odor, we can suspect a leakage   by its unpleasant smell. But  while cooking  dishes with variety of smell, recognizing the LPG smell may be  little bit difficult .

Gas  sensor circuits are very common nowadays but circuits having complications and confusions on sensor connections.. I have tried  my best  to  introduce  a very simple circuit,  which is  tested OK. Heart of  this circuit is  MQ 6  gas sensor, which is very sensitive for LPG ,iso butane & propane.

MQ 6 has an inbuilt heater where we have to supply 5V DC  or AC  for heating the coil. when coil is heat,Presence of  LPG get sensed by the electrodes inside and the output goes high. This output is fed to  the base of  BC 548 and  buzzer get ON . This is the basic theory of circuit.
Assemble this circuit and  switch on the power.first we have to  set the preset to hear the buzzer sound in the absence of LPG. then slowly rotate the preset PRECISELY  to just eliminate the buzzer sound. Now  light up a cigaratte  lighter( cigarette lighter use butane) and  blow off  the flame with pressed condition.Bring the lighter (without flame)  near the sensor. you can hear the buzzer beep loudly.Check with LPG also for fine tuning of  preset .
if look at MQ 6 may lead you  confusion because of its 6 pins .Actually 4 pin outs is sufficient for this ckt.
(ref picture.) leads A and A  to be shorted . B and B to be shorted.H and H  is the heater pins,where polarity is not an issue. AA  and  BB also can  inter change.  Only  4  pin outs   to be used for the circuit.

given ckt is proved one(see video)  and if  you change the value of components or voltage or current, this circuit may not function.More over, MQ 6 sensor voltage should not exceed 5.1 voltage in any situation.
Where we can procure MQ 6  sensor?  You can ask any electronic component dealer or you can get it by online shopping.( eg: www.electroncomponents.com)This costs around 150 - 175 Indian Rupees.
For the power supply  of this ckt, I have used an
old mobile charger  with 6V ,800mA as the power supply . When the LPG concentration in air is 200 to 10000 ppm(particle per million), sensor will detect and trigger the transistor .Preset adjustment is very important in this circuit. When gas is switch off,then also  buzzer remains  on for few seconds or may be 1- 2  minutes, Do not try to connect additional relay in this ckt because chance of spark between relay  contact may leads to fire . In the video, buzzer hole is blocked because of its ear piercing sound irritation during my trials.sensor is kept around 30 cm  away from burner and  within 6-7 seconds  buzzer statrts beeping.

Thanks & Regards
Vineesh Kodambattil

World's simplest " water level controller with high/low voltage cut off "

  World's simplest " Automatic water level controller with high/low voltage cut off "( Tested OK)

  This circuit  has  only  few cheap components and  very easy to assemble.  This circuit is a modified version of my previous post for  water level controller.Circuit can perform  4 operations  as below

1)  automatic switch on  water pump when water level  comes low in overhead tank

2) automatic switch off  the pump  when  tank get full

3) Low voltage cut off protection for pump to a set voltage, say below 160 V 

4) High voltage cut off protection  for  pump to a set voltage ,say  above 250V

                                             click circuit to enlarge

These all operations can be performed with this simple circuit. BC 547  will be  always in ON condition, till the water level comes down to lower level. switching ON the 547, keeps  187 off condition. when water level lowers, 547 loses its base voltage  and get off, results in switching ON   187 and relay connected to 187.Pump will switch off only when water rises to touch the tank upper probes.

If the voltage  become  low, while pump ON condition,187 loses its base  voltage through zener and relay get cut off.

If the voltage become high,zener connected  to  547  deliver  base voltage  to 547 . This condition switch ON  547 and ground the base of 187,resuting relay cut off.

Adjust the presets for the required cut off voltages. Relay contact Ampere rating is given as" x"  in circuit because you have to choose  a relay with  contact ampere according to the pump HP.Only 3 wires are needed to overhead tank

230V TO 1 WATT LED DRIVER

230V TO 1 WATT LED DRIVER (tested OK)

Driving a 1W  LED  with mains  is a simple thing. But to glow the LED with its maximum light efficiency,long life,  and less cost  etc are  not  so simple. We need 300-350 mA,with 3.6 volt to drive the LED with its maximum efficiency.When we try to increase the ampere in a transformerless supply,initial surge also will increase, which may damage the LED.  If we use Zener to control the voltage ,may result in zener damage  because of heating of zener.Those who do experiments with transformerless power supply may experienced such damages due to over heat ,In this circuit, 5 diodes are connected  between  positive and negative pole for getting an out put of 3.5 volt approximate. Since  1N 4007 can handle 1amp at 1000V, gives better result than zener.10uf/250 V electrolytic capacitor can prevent surge voltage to some extent.This circuit can deliver  250 mA ,but you can use additional capacitor for getting more current(upto 350 max) and light intensity accordingly.

click circuit

5 series diodes get little heat while lighting LED,but quite normal.even, provide little ventilation .

Always remember you are with live mains. Do not touch any of the points when connected with mains supply.soldering or  repairing the circuit should not be done if the mains connection is not removed

Thanks & Regards

Vineesh Kodambattil

Transformerless power supply

                Transformerless power supply,750 mA,12V(tested OK)

                                        We know many transformerless power supply circuits  which produce more than 100 mA by means of capacitance resistance and bridge construction. In fact, that circuits   may be  correct in theory,but if assemble practically,the current limiting resistors and zener get terribly heat and  damage  in short period. Even we use high watt resistors and zeners,things will be the same.Actually speaking, there is no need of current limiting resistor for high ampere transformerless circuits. After passing through  poly caps,We should allow the current to flow immediately as possible to the  opposite pole of AC.That is the safest way of handling  such circuits.The more we try to restrict current by resistor,or Zener, the more will be the heating.For eg,using 2.2uf cap  we obtain 150mA  max . Using zener, 3V ,Will produce less heat  than  a 12V, in same amperes.( same circuit.) If we increase the value of zener, to 9,12,15,16 so on, you can observe more heating of zener and current limiting resistors if any.

Here I have given  a circuit for 750 mA ,12 V DC  using 11uf capacitor.(2.2uf X 5 nos).

in this circuit, Triac will bypass current flow immediately to the opposite pole,by only supplying  the required volts  for bridge.if we reduce the value of 10k,more current flows through  triac and  bridge will get less volts accordingly. If phase of 230V is connected to parallel caps end,(top side in figure) will  reduce the chance of shock hazard ,since the other end of caps are  as same as neutral line and also all other points  do not have any shock potential. If  AC Neutral  point  is connected to  cap end,  all points will be as same as live....   So DO NOT TOUCH  any of the points even,phase and neutral are  connected in safest way. Triac or any other components  will not get more heat in this circuit. Loose contact to the AC mains connection may damage triac since immediate charge and discharge of 5 caps together due to loose contacts,produce high surge which cannot be widtstand by  triac . so connect  AC by means of proper  plugs only.Always be careful when work with mains.....


                                       Thanks & Regards
                                       Vineesh Kodambattil

How to check your remote control unit is working

   If your remote controlled equipments like TV,DVD etc are not functioning with remote button press, How do you know the problem is with your equipment or your remote?Almost all people know how to inspect the remote control  unit of   TV,DVD  etc. This post is meant for minority of people who don't know that.
                As you know remote control unit is producing  infrared rays in pulse form on each press of any buttons.  unfortunately infrared light is not visible with naked eye. Take your Mobile phone  camera and view the infrared LED through the camera.Press any button and see the infrared light produced from  the remote LED. If you bring it near a radio and press you can hear some pulse voice also.
See the video  taken in a mobile phone,which make the infrared light visible

Thanks & Regards

Vineesh Kodambattil

Simplest multivibrator,mains operated

            Simplest multivibrator,mains operated(tested OK)

             I have been  thinking of a simplest alternate led flasher with main supply 230V ,without any transistor since last few months.After many  days  of trial and error,at last i have succeeded in that task. This is a simplest mains operated  multivibrator  without any transistor. ckt working well  fine for last few  months continuously.Cost of this  comes  around 6 to 7 Rs  or less only.

When apply 230V,Cap c1 starts charging.

while cap charging,led2, (series with cap) lights. DB3  get less than 30V while cap charging and does not conduct. After full charge of cap, diac conducts and  led1( series to diac) lights,n cap discharge thru 1N 4007 ,that time LED2  light get dim ,which gives alternate blinking effect.

1.8K Resistor series to led1 is more than the requirement ,but given for matching the light intensity with LED2. 

                                                         
                                                                            circuit  (click)

             R1-47K,R2-1.8K,D1,D2-1N4007,D3- DIAC DB3,C1-47uF/63V,

                        Thanks& regards

                        Vineesh kodambattil

simplest waterlevel controller with high low voltage cutoff

     simplest water level controller with High/Low voltage protection(tested OK)

                                          this is a  ckt for a very simple and cheap water level controller. This  ckt is only a basic portion of my own marketed product having unsafe voltage cutoff ,dry run cut off and LED & alarm indications and overall protection .Any way, given ckt includes automatic water level control and high /low voltage cut off. sorry for cannot post  the entire ckt  due to limitations.WATER LEVEL CONTROLLER  ckt is  not new concept since we can find 100s of ckts  for water level controller in many sites and texts.But This ckt is  simplified with least no: of cheap components. water level sensing and high voltage sensing is doing  with same transistor. I used to put all my ckts in observation for a few months and found this ckt OK. but recently some problems highlighted by some customer,which i will definitely write down  the end of this post.

CIRCUIT DESCRIPTION

When the water level in over head tank is sufficient , points B & C  are closed through water and keeps T2   in ON condition .So  T3 will be off , resulting the motor in off condition. 

When water level lowers  below  B &C,  T2  gets off  and   T3 on, which  switches  the relay and  pump ON (pump connections not shown in ckt). Pump  get off  only when water  rises and touch the point  A  only , because point C becomes  neutral condition when T3 get ON. The pump  switches on again only when the water level comes down below B & C .

Presets VR2 is to be set to a high voltage cut off, say 250V when the voltage rises above 250V during pump ON  condition, T2  gets ON, and relay  off.

Preset VR1 is to be set to a low voltage cut off say 170V. T1 will be ON until zener z1 loses its breakdown voltage when voltage lowers to 170V,  Z1  will not conduct and T1  stays OFF, which delivers  a base voltage  to  T2 , resulting relay off.

T2 is handling the major role in this ckt. (high voltage cut off boards based on transistors,available in market can be easily integrated to this ckt)

Electronic components in this circuit worked very fine, but recently some  problems were  observed:

1) Minor deposits on sensor wire due to electrolysis in water, needed to be cleaned in 2-3 months( this problem is minimized  now by applying  ac voltage to sensor wire by means of additional ckt, which  will be posting  later)

2) Due to relay contact terminal sparks, generated every time during initial current pull of pump, contacts get worn out gradually.which tend to heat the pump because off in-sufficient  current flow to pump  (observed, new pumps works fine. older pumps heats up more) .

For avoiding this problem, additional motor starter  must be used, so that relay's function is limited to control the motor starter only, and pump never heats up.

                                           circuit( click)

PART LIST

R1,R11   - 100K

R2,R4,R7,R9,- 1.2K

R3  -10K

R5  -  4.7K

R6  -  47K

R8,R10  -10E

R12  - 100E

C1   -   4.7uF/16V

C2   -   220uF/25 V

D1,D2,D3,D4- 1N 4007

T1,T2   -     BC 547

T3          -    BC 639( try 187 )

Z1,Z2-    Zener 6.3 V,

VR1,VR2- 10K PRESET

RL - Relay 12V 200E, > 5 AMP CONT ( According  to pump HP)

                                                          Thanks & regards

                                                          Vineesh Kodambattil.