how to increase voltage across a 12v dc motor

[SaadKhan]

i am tryin to make a circuit through which i have to control a 12v dc motor. i am supplyin a 12v dc i/p. what should i do without using any transistor r amplifier to run a motor when light falls on ldr ???

 

[dselec]

Depends on the ldr ... send light versus dark resistance range .
u may be able to drive a high resistance relay in series to the relay or use opto.

Or you could use a switch and put it on/off at a speed of 50 times a second with your fingers , or 25 times a second or 15 times... thus getting control
sorry couldn't help it just joking ....ha...ha...ha...:-D:-D:-D
more if its a micro motor taking very little current it will work ldr in series to motor.
just thought about it now sure if one ldr can take say max 1 ma and u need 100ma u will need 100 ldr and now i am not joking i saw on ebay sales of 200 ldr for 10$ only last year
**broken link removed**

 

[papunblg]

i am tryin to make a circuit through which i have to control a 12v dc motor. i am supplyin a 12v dc i/p. what should i do without using any transistor r amplifier to run a motor when light falls on ldr ???

That depends upon how you like to control your motor with LDR.
options:-
1. Just on - off the motor in presence or absence of light. And the motor gets full 12 volt when on.
2. Gradully increase the motor speed as the intensity of light on LDR increases.

 

[SaadKhan]

thank to both of u but still i think em not providin u a complete sense what i am exctly tryin to say.. here em attaching figures and this circuit is working fine enough with transistor when there is no light on ldr, motor works n when with full light resistance of ldr decreases to min 500ohm now the relay changes it's contact like in the second figure and motor stops nw ... so my qustion is simple tht is there a possibility to do a same workin without using a transistor r any other amplifier ?? i have heard tht it is possible by using diffrnt combinations of resistor but em failed to do so....

btw thans again (=

 

[dselec]

!) after u write some thing press right button on mouse and ask for "check spelling" so we will understand u better
2) i answered your question only if u use relay in series with ldr it will work, your relay should be 450 ohm min . and u will need 3-4 ldr in paralel
https://media.digikey.com/pdf/Data ...Fs/DSS7, MSS(2, 7) , MVS(2, 7), PRM(A, E).pdf

 

[papunblg]

Without a transistor? Exactly what you want to do?

 

[SaadKhan]

yup i mean to make a circuit without any transistor.. anyways i got ur point using relays..thnkx btw

 

[dselec]

U haven't told us the motor specs..current with/without load

 

[SaadKhan]

i also duno abt the amp of motor :s its just a simple dc 12v motor which we usually see in our toys :/

 

[papunblg]

i also duno abt the amp of motor :s its just a simple dc 12v motor which we usually see in our toys :/

Why you want to avoid "without using a transistor r any other amplifier"?
What you want to do with this motor(12V toy motor) "without using a transistor or any other amplifier"

 

[dselec]

Sorry not good enough connect the motor to your supply and check current with /without load electronics is not for half backed idea, either u do it right or burn your motor and pwr supply as well or do more damage using your gadged.