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http://www.digikey.com/mkt/newt032/panasonic/ABJ0000CE4.pdfYou won't find ceramic capacitors much over 1 uF.
What kind of cap and what value should I use to smooth out the DC
before I feed it to the regulator (LM 340T12)? Is there a formula for
this
cap value? Is anything else required?
I use the good old formula C * dV = I * dt"Harry Muscle" <fake@AT@e-mail.com> wrote in message
news:3fde16cb$1_1@corp.newsgroups.com...
What kind of cap and what value should I use to smooth out the DC
before I feed it to the regulator (LM 340T12)? Is there a formula for
this
cap value? Is anything else required?
The "finger-in-air" figure I have used for many years is "2000uF per amp".
So, if you need only 100mA, use 200uF, and then put it into your
regulator. Remember to rate the voltage high-enough (eg 24v ac transformer
often gives about 30v under low load, multiply by 1.4 (if using full
bridge rectifier) so I'd select 50V working).
Thanks, that means that if I want a ripple of no more than 10V, current ofPaul Blitz wrote:
"Harry Muscle" <fake@AT@e-mail.com> wrote in message
news:3fde16cb$1_1@corp.newsgroups.com...
What kind of cap and what value should I use to smooth out the DC
before I feed it to the regulator (LM 340T12)? Is there a formula for
this
cap value? Is anything else required?
The "finger-in-air" figure I have used for many years is "2000uF per
amp".
So, if you need only 100mA, use 200uF, and then put it into your
regulator. Remember to rate the vol high-enough (eg 24v ac
transformer
often gives about 30v under low load, multiply by 1.4 (if using full
bridge rectifier) so I'd select 50V working).
I use the good old formula C * dV = I * dt
Where C is the smoothing capacitance, dV is the desired ripple
( ak
to peak), I is the desired load current and dt is 5mS for full wave
recification.
IAn
Looks OK to me. Remember the bottom of the ripple needs to be comfortably"Ian Bell" <ian@nowhere.com> wrote in message
news:bs80be$13p$1@news.ukfsn.org...
Paul Blitz wrote:
"Harry Muscle" <fake@AT@e-mail.com> wrote in message
news:3fde16cb$1_1@corp.newsgroups.com...
What kind of cap and what value should I use to smooth out the DC
before I feed it to the regulator (LM 340T12)? Is there a formula for
this
cap value? Is anything else required?
The "finger-in-air" figure I have used for many years is "2000uF per
amp".
So, if you need only 100mA, use 200uF, and then put it into your
regulator. Remember to rate the vol high-enough (eg 24v ac
transformer
often gives about 30v under low load, multiply by 1.4 (if using full
bridge rectifier) so I'd select 50V working).
I use the good old formula C * dV = I * dt
Where C is the smoothing capacitance, dV is the desired ripple
( ak
to peak), I is the desired load current and dt is 5mS for full wave
recification.
IAn
Thanks, that means that if I want a ripple of no more than 10V, current of
0.5A I would have:
C*10 = 0.5 * 0.005
C*10 = 0.0025
C = 0.00025
or C = 250uF
Is that correct?
Thanks,
Harry
You also have to have a capacitor with a ripple current rating that isThanks, that means that if I want a ripple of no more than 10V, current of
0.5A I would have:
C*10 = 0.5 * 0.005
C*10 = 0.0025
C = 0.00025
or C = 250uF
Is that correct?