Voltage regulators in series?
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Posts: 46,084
Hello all,
I've got a working radio control circuit for my electric
wheelchair platform. To step the voltage down from 24V to power my circuit
can use a 12V regulator (ie. 7812) and then a 5V regulator (ie.7805)? I
know the 7805 can handle 24V , but it gets pretty hot and I'm wondering if
I can have this dissipated by two devices...
Cheers, Duncan
I've got a working radio control circuit for my electric
wheelchair platform. To step the voltage down from 24V to power my circuit
can use a 12V regulator (ie. 7812) and then a 5V regulator (ie.7805)? I
know the 7805 can handle 24V , but it gets pretty hot and I'm wondering if
I can have this dissipated by two devices...
Cheers, Duncan
Comments
No problem. Just be sure to use capacitors at each input/output to prevent
oscillations.
Ray McArthur
> I've got a working radio control circuit for my electric
> wheelchair platform. To step the voltage down from 24V to power my circuit
> can use a 12V regulator (ie. 7812) and then a 5V regulator (ie.7805)? I
> know the 7805 can handle 24V , but it gets pretty hot and I'm wondering if
> I can have this dissipated by two devices...
Another excellent choice is the LM2940CT (5V 1A LDO) regulator, made,
amongst others, by National Semiconductor. It features extra protections
that the 7805 doesn't have, and can handle up to 26V.
Cheers,
Mike
>
Mensaje original
> De: rjmca [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=k4BRGBhCAYQ9yBlfrMriaVGhzaYMx7FOAnWaWAYDig5JvxQgIhJ-5wp6uNjOhxhle_Wp6pTB6mMMTYg]rjmca@w...[/url
> Enviado el: domingo, 16 de julio de 2000 6:40
> Para: basicstamps@egroups.com
> Asunto: Re: [noparse][[/noparse]basicstamps] Voltage regulators in series?
>
>
> Duncan:
>
> No problem. Just be sure to use capacitors at each input/output
> to prevent
> oscillations.
>
> Ray McArthur
>
> > I've got a working radio control circuit for my electric
> > wheelchair platform. To step the voltage down from 24V to power
> my circuit
> > can use a 12V regulator (ie. 7812) and then a 5V regulator (ie.7805)? I
> > know the 7805 can handle 24V , but it gets pretty hot and I'm
> wondering if
> > I can have this dissipated by two devices...
>
>
>
>
>
>
>
> Duncan:
>
> No problem. Just be sure to use capacitors at each input/output
> to prevent
> oscillations.
Thanks Ray and Miguel, I'll do that. I'm also going to heatsink them both
right to the side of the case. I don't need the additional protection of
the LM2940 as the control box circuitry (where I'm drawing power) is
already well isolated from the two batteries.
Duncan
> I've got a working radio control circuit for my electric
> wheelchair platform. To step the voltage down from 24V to power my
> circuit can use a 12V regulator (ie. 7812) and then a 5V regulator
> (ie.7805)?
Yes this is one way, a better way would be one of National's
switching regulators. These only require 2 caps and a coil and will
not waste power as heat.
> I know the 7805 can handle 24V , but it gets pretty hot and
Some are spec'd up to 35V max in, but remember your have
16.5V(24-5-2.5)*Iout worth of power to dissipate.
> I'm wondering if I can have this dissipated by two devices...
>
> Cheers, Duncan
>