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.