Re: Zener diode regulator?
On Wed, 01 Feb 2006 10:22:07 -0700, Jim Drew <msdei@xxxxxxxxxxx>
wrote:
>John_H wrote:
>
>> "Jim Drew" <msdei@xxxxxxxxxxx> wrote in message
>> news:43e0e7bd$0$8270$6d36acad@xxxxxxxxxxxxxxxxxxxxx
>>
>>>I am revisiting a problem that was posted a few months ago. I have tried
>>>numerous solutions, but nothing on the complex side of things will work for
>>>this application.
>>>
>>>The problem is that I need to be able to convert an input voltage varying
>>>from 20 volts to 80 volts (at up to 100 amps) to 12 volts (at 500ma to 1
>>>amp).
>>
>>
>> <snip>
>>
>> Are you able to dissipate 68 watts in this "simple" circuit? If you're
>> supplying 1A through a series element (as opposed to a switcher) you *will*
>> disspate at least 68 watts.
>
>This circuit is to power a 5 volt regulator for a CPU, and to provide
>gate drive power for MOSFETS. The circuit probably needs no more than
>100ma, but I wanted to have a reserve for future use of LEDs and such.
>
>I don't think I will need to handle 68 watts of power. Like I said, a
>12 zener with the proper resistor for 80 volts works great to provide
>whatever current level needed. However, as the voltage drops, the
>current drops, making this solution unusable with a variable power
>input. I have seen some sort of voltage follower type of circuit that
>connects to a zener diode to provide a constant current. An op-amp
>could do something similar I suppose, but I have no idea how this would
>be wired.
Critical question: when your existing circuit is working at 80 volts
input, what resistor value is in series with the zener?
John
.
Relevant Pages
- Re: Basic MOSFET Q., Also, "ground" vs "positive", & voltage matching
... power systems, ... the designer decided to call "zero volts", and to use as a reference ... when measuring voltages elsewhere in the circuit. ... voltage is 2.5 volts. ...
(sci.electronics.basics) - Re: Help needed designing simple circuit
... so I'm trying to come up with a simple (maybe even elegant) solution ... This gave me a nice 5 volts when the power was ... circuit when the light comes on. ...
(sci.electronics.repair) - Re: Trouble With A Very Simple MOSFET Amplifier
... I've breadboarded a circuit out of Forrest Mim's _Getting_Started_.... ... power source: 8.61V ... The gate should have about one to four volts with respect to the ...
(sci.electronics.basics) - Re: My Stove
... Resistance is what causes the voltage drop. ... So power is volts times amperes. ... The last one is probably the easiest to apply to the range circuit. ...
(sci.electronics.basics) - Re: ultrasonic speaker simple amplifier
... output on the speaker above what I get from the 555 timer pin 3 output. ... Help on the output circuit to switch a power transistor with the speaker ... I have used 18 volts for this type circuit, ...
(sci.electronics.design) |
|
