Re: Step-down Transformer, AVR thread (and Variac)

where are the wips carving your way out of that onkyo amp cover with a nicely fitting outlet?

btw...the 3600 makita router will simply bown to whatever speed that step down transformer with variac will dictate.
😉

Re: Step-down Transformer, AVR thread (and Variac)

Bro you reminded me to blow off sawdust inside my AVR. Took a few pics too after cleaning.

Re: Step-down Transformer, AVR thread (and Variac)

now i see the innards of the stac!

instead of the usual square box it is surprising for me to find that doughnut shaped winding core special to that nippon gem.

plus the brushless fan.

that makes it expensive???

but i wish the wires get tidied.

Re: Step-down Transformer, AVR thread (and Variac)

where are the wips carving your way out of that onkyo amp cover with a nicely fitting outlet?

It's an interference fit! Was supposed to bolt it but no need. Surprisingly went well... wish all the panels were like it. Started with the drill-the-perimeter method, and used files with the coarse-medium-fine progression of work in mind (the width of drafting tech pens is a good guide- .5mm is coarse, .3mm is medium.) File, test fit, file, test fit. One whole evening. Very relaxing actually, when you devote your mind in just one task. Beveled it so it's tighter on the surface. Then when the difference went below 0.10mm... tapped it home with a hammer (aluminum is soft and malleable anyway.)

FWIW, the aluminum fascia routes well.

@JayL

I regularly watch if a STAC or Stavol comes up in TPC ... the variac (toroidal core) itself pretty much has indefinite life. Maybe the only things that go bad would be the capacitors after ~20 years or the brush. I don't want to know how much a STAC 1500 watter would cost nowadays =).

Relay type AVRs respond quicker, however a servo'd variac like the STAC introduces less noise to the line and can dial in the voltage more finely.

Re: Step-down Transformer, AVR thread (and Variac)

Have you seen these? On the last pic it looks like these use torroids too.

http://www.sulit.com.ph/index.php/view+classifieds/id/1857891/Automatic+Voltage+Regulator+and+Stabilizer+%28Servo+Motor+Control+%29?referralKeywords=stac+voltage+regulator+1500+watts

Re: Step-down Transformer, AVR thread (and Variac)

^
There's a cheap AVR (maldol brand) in the compound, rated at 500 watts, it gives off a lot of heat by just powering a single TV... wouldn't trust it to run 24/7 (fridge.) The clip that holds the outlet against the chassis snapped. I dunno what middle quality brand- the toptul of AVRs- is, but now i'm sure it ain't maldol =).

Re: Step-down Transformer, AVR thread (and Variac)

I've seen variac's sold locally in the market with adjustable voltage. Do you guys think there are those with adjustable amps..

Re: Step-down Transformer, AVR thread (and Variac)

Nice and timely thread fir me. I have a 110V Bosch TS coming. Which brand/model of step-down would you recommend?

I probably don't have the talent to retrofit a Variac into an amplifier.

Re: Step-down Transformer, AVR thread (and Variac)

I've seen variac's sold locally in the market with adjustable voltage. Do you guys think there are those with adjustable amps..

What do you mean clayfigure? Adjustable current? An AVR or a transformer has a rating which you shouldn't exceed, say 1000W -that's about 5 amps @ 220v (since power is voltage times current, Watts= Volts X Amps.) So the bigger the better ;). The current being drawn is up to the equipment/tool. A half hp motor will draw a half hp worth of current (~3 amps.)

I'd de-rate those chinese ones by 70% of the touted capacity personally... can't back it up but just a hunch. I've seen the gauge of the copper's thicker on japanese Stacs compared to taiwanese/china ones with the same KVA rating.

A Stac or Matsunaga AVR is in my perenial tool hitlist. (Just not gonna pay 6K for a 1KVA right now...)

====
How much watts is the bosch TS? Given that manufacturers often give a rather optimistic rating, high inrush current of universal and induction motors, imho, i'll make the load 60% of the purported rating- especially on transformers which don't have a fuse.

====
Long term report for the variac? It's living an easy life. Rated at 3KVA (3,000 watts,) I don't have equipment to challenge it. Although i see the needle in the ammeter whiplash on start-up of inductive loads (motors.) Downside is it's HEAVY, not too transportable. Have used it to slow down an angle grinder (but not too much, cause the grinder might overheat.)

Re: Step-down Transformer, AVR thread (and Variac)

In my own experience I can fully recommend the Stac. It's what we used in my 20 years of work in the IT hardware business. Built like a tank. The 1.5KVA and 1KVA I have are almost 15+ years old now and works flawlessly.

I have no problem using the 1 KVA for my 110 volts angle grinder, sanders, polishers, MS etc... one tool at a time.

The only times I've seen these STAC break down is when the unit is set for 110V input then plugged to a 220V outlet. A misuse.

Re: Step-down Transformer, AVR thread (and Variac)

How much watts is the bosch TS? Given that manufacturers often give a rather optimistic rating, high inrush current of universal and induction motors, imho, i'll make the load 60% of the purported rating- especially on transformers which don't have a fuse.

Sorry. Should've been more specific. The Bosch4100 TS is 15A so at 110V, that should be roughly 1.7kW. You mentioned derating by 60%, so should I be getting a step-down at 1kW? Add some headroom, should I get 1.5kW? Which brand/model would you recommend at this capacity?

Thanks!

Re: Step-down Transformer, AVR thread (and Variac)

I use the Stac 1.5KVA for the Bosch 4100 but have tried the 1KVA Stac too and it worked without any issue. However I recommend that proper ratings be computed for sure ball approach.

It might be worth to double check the AVR specs. Usually computed on a same source/output voltage ( ie 110V input - 110 volts output or 220V input - 220V output ). There might be a loss factor in the power rating if its is used for voltage step down or step up purposes.

Re: Step-down Transformer, AVR thread (and Variac)

must be paranoid, I use 2000w Panther (stepdown) for my imported shop tools, never gave me worries and hardly heats up... 😀 stops me from buying another when I get a bigger powertool...

Re: Step-down Transformer, AVR thread (and Variac)

must be paranoid, I use 2000w Panther (stepdown) for my imported shop tools, never gave me worries and hardly heats up... 😀 stops me from buying another when I get a bigger powertool...

LOL Yes Timb ...I'm with you on this one. Larger capacity is better for this type of stuff. No harm in a little over kill. 😎