[SOLVED] how to amplify 2 volts dc to 5 volts dc...

[nithin kamath]

hello, i am doing a circuit in which we are getting 1.98 volts output from an IC.... i have to connect this to a 5V relay... So now i have use an amplifier circuit to amplify 1.9V signal to 5V... So can anyone please help me about this.... How can i design the circuit using transistors and any simple components ...??


Thanks in advance...

 

[mister_rf]

You may use a NPN transistor, see the diagram..

 

[goldsmith]

Dear nithin
Hi
It depends on how much current do you need . if your current is very low , you can use a multiplier with diode and capacitor . but if you need higher currents you can use a simple boost converter .
Best Wishes
Goldsmith

 

[vinay r v]

thank u very much... i'll try this now... and i'll contact u for further details...

---------- Post added at 16:46 ---------- Previous post was at 16:45 ----------

You may use a NPN transistor, see the diagram..

thank u very much... i'll try this now... and i'll contact u for further details...

 

[varunkant2k]

You need to tell us, if 1.98V, coming out of the IC pin is digital in nature or Analogue. Do you have 2V(1.98V) supply? Nature of application?

 

[:pH]

Firstly describe your requirements , the thing is if enough current is availabe the relay can be operated even at 3V , so current ratings are more important

 

[nithin kamath]

You may use a NPN transistor, see the diagram..

Thank You sir, u made our circuit much simpler.... its working fine... :-D

---------- Post added at 20:35 ---------- Previous post was at 20:28 ----------

Firstly describe your requirements , the thing is if enough current is availabe the relay can be operated even at 3V , so current ratings are more important

You need to tell us, if 1.98V, coming out of the IC pin is digital in nature or Analogue. Do you have 2V(1.98V) supply? Nature of application?

Dear nithin
Hi
It depends on how much current do you need . if your current is very low , you can use a multiplier with diode and capacitor . but if you need higher currents you can use a simple boost converter .
Best Wishes
Goldsmith

Actually i am giving +5V supply to a decoder IC..... I have connected some relays at the output pins of the IC, so that when an output is HIGH,the relay switches another signal....

But the problem is At the output pins,when the output is HIGH am getting only around +1.98V and the Relay(5V) cannot respond to 1.98V.....

 

[BradtheRad]

Relay coils often draw greater current than an IC can put out. So your measured output voltage drops. The IC cannot energize the coil.

A transistor amplifier solves the problem (per post #2).

 

[:pH]

you can also use driver ic like uln2803 which incorporates darlington pair for high current output

 

[nithin kamath]

Relay coils often draw greater current than an IC can put out. So your measured output voltage drops. The IC cannot energize the coil.

A transistor amplifier solves the problem (per post #2).

Yes, i am facing the same problem... i was not knowing about this before..... and the transistor circuit in post #2 is not amplifying current, it just steers the output based on control signal......

Can u help me regarding this current isssue.....?? Can u please give me the circuit to amplify the current coming out of the circuit in post #2...? (or change that circuit to get the high current)

Thanks in advance..

---------- Post added at 19:02 ---------- Previous post was at 19:00 ----------

you can also use driver ic like uln2803 which incorporates darlington pair for high current output

uln2803 is not available here Can u help me with a transistor circuit to get the high current from the circuit in post #2....???

thanks in advance

 

[:pH]

See you can go for other driver ic like uln2003 , try foll link :

https://arduino.cc/forum/index.php?topic=51342.0

now if no driver ic is available then i will suggest

and use PULL-UP resistor on the output of your decoder ic

 

[BradtheRad]

Come to think of it, there are few relays which can operate on 5V. The only one I've been able to use was one specifically labeled 'high-sensitivity', which I got at Radio Shack.

Questions:

* Does your relay pull in when you connect its coil directly to 5V? Does it release when disconnected?

* Does its label state a value for coil ohms? Does it state a minimum amount for amps or volts?

* Can you measure how many amps can be drawn through the collector of the transistor, when 5V is applied at the base leg? This requires care because you don't want to fry the transistor. If you use a 1K resistor in the base leg, then the collector leg should pull a couple hundred mA. This may heat up the transistor. You should grip it between your fingers. Stop testing if it becomes too hot to hold.

* Does the collector shut off when zero V is applied to the base? In other words, does your meter show 0 amps through the collector when you reduce bias to 0 mA?

 

[nithin kamath]

Ok... finally i am getting 5V output from my decoder IC.... I have changed my circuit a little... I am going to use a 12V electro-mechanical Relay which is driven by a 555 timer IC which will output a larger current to relay.... I am not going to use any transistor..... I have attached the circuit diagram.... it is working fine in Simulation...

Is this circuit all right..??? Does it enables the 12V relay so that i can switch a 220v line.....???

With regards,
Nithin Kamath

 

[Syncopator]

..... the transistor circuit in post #2 is not amplifying current,

That is exactly what it is doing.
The transistor has about 4.4mA through its base-emitter junction. The collector-emitter current is equal to the value of the supply voltage divided by the relay coil's resistance.

 

[nithin kamath]

ok.... finally got it..... i think the problem was lack of fundamentals in circuit design.... Anyhow am a Computer Science student.. am a newbie in this field... Learning a lot of things from u all.... Thank u all for helping me in this issue.... I am marking this thread as [SOLVED] :-D

thankfully,
Nithin Kamath