[sdiy] power supply for casio CZ1000

[Adam Inglis (sdiy)]

These Casios draw a surprising amount of current. I own a couple of CZ-101s and if I’m not careful what supplies I plug in, they get noisy and start misbehaving in various ways. It’s nearly always because the current isn’t up to spec, not the voltage.
What’s the specified power requirement on the CZ-1000? Maybe go for something with some current capacity in reserve.

Adam
> On 23 Feb 2020, at 10:41 am, Ben Bradley <ben.pi.bradley at gmail.com> wrote:
> 
> Oh boy, here's another potentially cantankerous topic. I wrote my
> answers below, some others might have different opinions.
> 
>> Are all switching power supply wallwarts noisy?
> 
> No, but there are so many inexpensive things thesedays that it's hard
> to tell what might be noisy. I seem to recall a statement here in
> recent years that "switching supplies are a lot better (noise wise)
> than they used to be." That might even be true on average, and good
> brand names and suppliers surely make well-filtered, low noise
> switchers thesedays, but you have to know the brand names and such,
> else you'll probably get cheap noisy junk.
> 
>> Should I use a power
>> supply with a transformer instead?
> 
>   What you're thinking of is a big, heavy 50/60Hz transformer that
> has traditionally been used in "wall warts" and electronic equipment
> for many decades (all power supplies use transformers, but switch-mode
> power supplies use switch frequencies around 100kHz and up so that
> much smaller transformers can be used).  They're usually better than
> switching supplies in many ways, but can have their own problems. The
> laminations can be loose and cause an audible buzz at the line
> frequency. Inexpensive rectifiers are usually slow to switch off, and
> when they do they cause a high frequency RF "ringing" that gets into
> sensitive circuits and makes an electronic buzz in audio circuits. But
> these problems are generally easier to fix than many switching supply
> problems.
> 
>> Are these transformer power supplies
>> called linear?
> 
>   in general, yes.
> 
>> Are all power supplies that use transformers quieter in
>> audio applications?
> 
>   In general, yes.
>> 
>> I have a 9V power supply that uses a transformer that has a big enough
>> power rating but when I test the output I read 12V. Will this damage my
>> synth?
> 
>   A meter reading will give an unloaded reading which is usually
> higher than the rated output, but it will be closer to rated output
> under load. This should be fine.
>> 
>> Can anyone recommend a source for a quiet 9V, 1A wallwart? When I search
>> for 9V, 1A regulated power supply all I get are switched supplies.
> 
>   Years ago I got the "big heavy" linear wall warts at thrift stores,
> but by now they're almost all switchers.
> 
>   It's almost the only thing that's made thesedays for a variety of
> reasons. They're smaller, lighter, cheaper to make, and due to the
> light weight cheaper to ship.They can often be filtered for audio, but
> sometimes it's easier to use and filter a 60Hz supply. The market for
> 60Hz supplies is for the most part too small to justify making them,
> though Digikey or Mouser might have a few. Worst case, you can still
> order 60Hz transformers, rectifiers, capacitors and possibly regulator
> chips and make your own linear supply.
> 
>> 
>> Thanks. JoeF.
>> 
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