Re: LM31T as AC voltage regulator for Commodore computers PSU

From: Clockmeister <clockmeister_at_internode.on.net>
Date: Sun, 19 Jun 2022 12:50:29 +0800
Message-ID: <c0dd1638-3da0-14a1-8f20-333f6d5d8492_at_internode.on.net>
Something like this 
https://www.amazon.com/Alesis-SR-16-SR16-Power-Supply/dp/B08BJLRN9X?ref_=ast_sto_dp&th=1

On 19/06/2022 12:40 pm, Clockmeister wrote:
> DC power packs are switch mode supplies but those with unregulated AC 
> output which are commonly available have a transformer.
>
>
> On 19/06/2022 9:58 am, ocleide_at_earthlink.net wrote:
>> That surprises me.....it seems like the most "commonly available" 
>> wall-warts these days use switching power supply 
>> circuitry..........maybe it differs by country?
>>
>> -----Original Message-----
>> From: Clockmeister <clockmeister_at_internode.on.net>
>> Sent: Saturday, June 18, 2022 8:51 PM
>> To: cbm-hackers_at_musoftware.de; tokafondo@tokafondo.name
>> Subject: Re: LM31T as AC voltage regulator for Commodore computers PSU
>>
>> 9VAC transformers are commonly available brand new in plug-packs
>> (wall-warts) or as individual components from most electronics 
>> suppliers.
>>
>>
>>
>> On 19/06/2022 5:17 am, tokafondo_at_tokafondo.name wrote:
>>> I will only say that this is an actual Commodore (and retro computers)
>>> desert. And most 9V adapters I've ever seen are from xDSL routers, AP
>>> and modems, long ago discarded.
>>>
>>>
>>>
>>> 18 de junio de 2022 22:12, "Mike Stein" <mhs.stein_at_gmail.com
>>> <mailto:mhs.stein_at_gmail.com?to=%22Mike%20Stein%22%20<mhs.stein@gmail.com>>> 
>>>
>>> escribió:
>>>
>>>      Well, he's in Spain and you're in Italy; maybe you treasure the
>>>      old traditional ways more than he ;-)
>>>      I don't know offhand how constant the 9V load of a C64 is but I
>>>      would think that a carefully selected resistor with maybe a couple
>>>      of Zeners to clamp any overvoltage might do the trick.
>>>      m
>>>      On Sat, Jun 18, 2022 at 2:27 PM Francesco Messineo
>>>      <francesco.messineo_at_gmail.com
>>>      <mailto:francesco.messineo_at_gmail.com>> wrote:
>>>
>>>          On Sat, Jun 18, 2022 at 5:42 PM <tokafondo_at_tokafondo.name
>>>          <mailto:tokafondo_at_tokafondo.name>> wrote:
>>>          >
>>>          > TI's version of the LM317T's datasheet has something
>>>          interesting to see in its page 15.
>>>          >
>>>          > It can be seen only in TI's datasheet, and not others AFAIK.
>>>          >
>>>          > They show how to use two LM317T IC in a way that from a
>>>          12VAC source, take it down to 6VAC. I'm sure that with
>>>          changing the values of the resistors needed, 9VAC can be got,
>>>          instead of the 6VAC of the example.
>>>
>>>          it is actually AC in the sense that there will be alternating
>>>          polarity
>>>          voltages, however that circuit will clamp the waveform voltage
>>>          to 9V
>>>          (or whatever you chose) as long as the input voltage is
>>>          greater than
>>>          the set voltage. So you'll get a kind of "flat-top" waveform.
>>>          I'd say it's not ideal (it adds high frequency harmonics, both
>>>          LM317
>>>          need to be heatsinked...)
>>>          I have never had any difficulty in finding 9VAC transformers.
>>>
>>>          Frank IZ8DWF
>>>
>>>
>>>
>>
>>
>>
>
>
Received on 2022-06-19 07:00:49

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