Maker Pro
Maker Pro

Stepping up voltage

komalbarun

Nov 25, 2011
67
Joined
Nov 25, 2011
Messages
67
All i want to know is if this circuit will work? if not, then why will it not work?
 

Attachments

  • step_dc.png
    step_dc.png
    6.4 KB · Views: 160
Last edited:

duke37

Jan 9, 2011
5,364
Joined
Jan 9, 2011
Messages
5,364
It should 'work' but it will depend on the component values as to what you get.

R3 (1k) will limit the power and you may get out less than you put in.
 

BobK

Jan 5, 2010
7,682
Joined
Jan 5, 2010
Messages
7,682
A better circuit would use a full H-bridge. DC to AC inverter.

Bob
 

CDRIVE

Hauling 10' pipe on a Trek Shift3
May 8, 2012
4,960
Joined
May 8, 2012
Messages
4,960
Yes, R3 is an unrealistic value. Way to high.

Chris
 

duke37

Jan 9, 2011
5,364
Joined
Jan 9, 2011
Messages
5,364
You will need to specify the power supply and the components.
Fets will be better than npn transistors if they are being driven by logic circuits since they take little power to drive. They are also more efficient.

You can look up H-bridge yourself if you wish. It is a circuit which can change the polarity of the output, often used to reverse DC motors. It will have protection from the case where the two transistors are on for a very short time (shoot through) during switch over. Your circuit does not have this protection which may be a problem.
 

komalbarun

Nov 25, 2011
67
Joined
Nov 25, 2011
Messages
67
You will need to specify the power supply and the components.
Fets will be better than npn transistors if they are being driven by logic circuits since they take little power to drive. They are also more efficient.

You can look up H-bridge yourself if you wish. It is a circuit which can change the polarity of the output, often used to reverse DC motors. It will have protection from the case where the two transistors are on for a very short time (shoot through) during switch over. Your circuit does not have this protection which may be a problem.

shoot through = both transistors on?
so this is a possible case?

btw thx to have talked abt h bridge. I knw a lot more now :)
 

duke37

Jan 9, 2011
5,364
Joined
Jan 9, 2011
Messages
5,364
Yes, shoot through is a term used where one transistor turns on before the other is fully turned off. This may not be a problem if the current is limited and it does not occur often.
An invertor running at 100kHz with a 1microsecond overlap will have problems, one running at 10kHz with the same overlap may not have a problem.
 

komalbarun

Nov 25, 2011
67
Joined
Nov 25, 2011
Messages
67
Yes, shoot through is a term used where one transistor turns on before the other is fully turned off. This may not be a problem if the current is limited and it does not occur often.
An invertor running at 100kHz with a 1microsecond overlap will have problems, one running at 10kHz with the same overlap may not have a problem.

lol I understood what you said ! I surprise myself sometimes lol xD

Thanks a lot for the help :)
 

CDRIVE

Hauling 10' pipe on a Trek Shift3
May 8, 2012
4,960
Joined
May 8, 2012
Messages
4,960
Yes and so does TTL. With high speed comes shoot-through and subsequent spikes on the supply rails. This is why good supply rail bypassing is important. On an H-Bridge it can be reduced greatly but at the expense of switching speed.

Chris
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,510
Joined
Jan 21, 2010
Messages
25,510
A good H Bridge driver will turn one transistor off before turning the other one on to reduce or eliminate shoot-through. It's especially an issue with mosfets.

Actually CMOS has interesting issues with shoot-through. Sometimes these are called "crowbar currents"
 

CDRIVE

Hauling 10' pipe on a Trek Shift3
May 8, 2012
4,960
Joined
May 8, 2012
Messages
4,960
I imagine you're referring to a design that comprises more than your basic 2 NPN's, 2 PNP's.

Chris
 
Top