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lab power supply

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glinjik:
after looking at various ways to control a fan rather than just having it running found a little 555 timer fan control uses a npn transistor and thermistor so I’ve incorporated it into the scheme but before I build it in was wondering if any of you enlightened chaps might cast your eyes over the scheme so far oh i re drew the 555 to reflect it in reality rather than schematically its easyer to follow for me

Ed.Kloonk:

--- Quote from: MarkF on December 14, 2019, 12:14:34 am ---Here are a few DIY circuits you can play with:

(Attachment Link)


--- End quote ---

Was going to start a new thread, but where's the fun in that when I can hijack this one.

The above PSU specifies garden variety parts. What if I wanted to feed in 12vdc for a output range of up to 9 volts. What is a good solution for that -5v reference using off the shelf parts?

Are those buck/boost IC's considered off the shelf?

MarkF:

--- Quote from: Ed.Kloonk on December 19, 2019, 11:17:15 am ---
--- Quote from: MarkF on December 14, 2019, 12:14:34 am ---Here are a few DIY circuits you can play with:

(Attachment Link)


--- End quote ---

Was going to start a new thread, but where's the fun in that when I can hijack this one.

The above PSU specifies garden variety parts. What if I wanted to feed in 12vdc for a output range of up to 9 volts. What is a good solution for that -5v reference using off the shelf parts?

Are those buck/boost IC's considered off the shelf?

--- End quote ---

If you don't need it to go below 1.2V, I believe you could use a slightly different version with a "single supply" or "rail-to-rail" op-amp. 
I think I would try a LM358 with 0V and 12V for its supply.    Edit:  Or the TL071 shown on the other version.
I'm not so sure you need a negative supply rail.

Ed.Kloonk:

--- Quote from: MarkF on December 19, 2019, 12:46:06 pm ---
--- Quote from: Ed.Kloonk on December 19, 2019, 11:17:15 am ---
--- Quote from: MarkF on December 14, 2019, 12:14:34 am ---Here are a few DIY circuits you can play with:

(Attachment Link)


--- End quote ---

Was going to start a new thread, but where's the fun in that when I can hijack this one.

The above PSU specifies garden variety parts. What if I wanted to feed in 12vdc for a output range of up to 9 volts. What is a good solution for that -5v reference using off the shelf parts?

Are those buck/boost IC's considered off the shelf?

--- End quote ---

If you don't need it to go below 1.2V, I believe you could use a slightly different version with a "single supply" or "rail-to-rail" op-amp. 
I think I would try a LM358 with 0V and 12V for its supply.    Edit:  Or the TL071 shown on the other version.
I'm not so sure you need a negative supply rail.

(Attachment Link)

--- End quote ---

Nice. Thanks.

David Hess:
Another way to make an adjustable current and voltage regulator without an operational amplifier is shown below.

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