Line Voltage Inconsistency

[drhulsey]

I frequently see members here having trouble because of the inconsistency of their AC Line voltage. I have had problems with this at gigs, as well. One simple way to avoid these problems, especially in your home workshop is to use an AC voltage regulator such as:
Tripp Lite 1200-Watt
Line Conditioner / Voltage Regulator LC-1200
Item #: DBL13683

# Automatically adjusts incoming voltage from 87 to 140V to computer grade 120V AC
# 1,200 joules AC surge suppression
# 4 protected AC outlets
# Complete brownout and over voltage correction
# 7 diagnostic LEDs display input voltage conditions
# Surge protection and EMI/RFI noise filtering
# $25,000 ultimate lifetime insurance
# Includes 6' AC power cable

These sell for about $125, but can be found on ebay at times for less. Of course, you can also find more expensive models

If this is common knowledge, I apologize for buggin' ya

[ic-racer]

# Automatically adjusts incoming voltage from 87 to 140V to computer grade 120V AC

In concept it sounds like a good thing for gigs. The problem with a standard Variac at at a gig is that you need someone with a voltmeter the check and adjust it.


I always thought it would be cool if someone would incorporate one of these 'mini' panel mount variacs into an amp (along with a panel voltage meter).

http://www.iseincstore.com/index.asp?Pa ... &ProdID=26

[paulster]

Tim

The only problem with some of these 'computer grade' ones is that computers don't require a very high grade power supply. In fact, since they all have switched-mode power supplies, you can happily supply a square wave and that's a lot cheaper to do since the transistors only have to switch on and off, rather than dissipate loads of heat when trying to deliver 50% of the voltage at points during the cycle.

I'm not saying this one falls into this category, but it might do, so it's always worth checking to see whether what you are buying outputs a pure sine wave. If it's a simulated sine wave or something similar then its probably a chopped square wave and not ideal for the linear power supplies in amps.

Paul

[drhulsey]

... The problem with a standard Variac at at a gig is that you need someone with a voltmeter the check and adjust it...

You also need someone to CARRY IT

... If it's a simulated sine wave or something similar then its probably a chopped square wave and not ideal for the linear power supplies in amps...

I hadn't thought of that I'll have to check the specs.
Thanks

[mhuss]

They say it's for "sensitive electronics, computer accessories and home theater equipment" and uses "reliable transformer-based voltage correction circuits"so I doubt the output waveform is too unreasonable, sounds like a multi-tapped autoformer with automatic switching.

Of course, this specific unit is not much use for folks outside of North America, but I'd be surprised if there were not 240v versions available abroad.

--mark

[paulster]

Mark

I didn't read the specs for this one but it does sound like a multi-tapped transformer with zero-crossing then.

I've seen lots of people recommending regular computer UPSes before; that was really my point. These devices generally aren't what you want to have feeding your nice linear power supply!

And, yes, we could do with some 240V versions of these. Furman have just discontinued theirs, seemingly.

Paul

[Guitarman18]

paulster, what do you do about the mains here in the UK. I'm in the process of trying to order some Heyboer trannies, however I know that our mains is supposed to be 230V, but here in my workshop it often reaches 245V. Do you order 230V or 240V PT's?
Sorry if this is slightly off topic, but it is a symptom of the same issue.

[Andy Le Blanc]

line conditioners can be a blessing...... theres a spot I play at where the
electrics are so bad that I plug into the conditioner that the PA is useing
so I dont get it in the mouth off the mic...... it seems to work great with
three instument amps and the PA..... no brown.... all good..... Ive heard
horror stories for years about line conditioners but so far my experience
is good if your conservation with the draw..... most of the stories Ive heard
involve large wattage sand circuits ......county fairs..... and gen sets....
I have discoverd a real need for one for my bench......when I can I will....

[LOUDthud]

I have several LC-1200's at my business. They use relays and a multi tapped boost-buck transformer. To eliminate voltage dropouts when switching between taps they momentarily short the transformer taps. This is ok on the regulated side but kicks noise onto the raw line side although there is some filtering and MOV clamps. The new ones are plastic cubes and not very durable. I have one at home that's almost 20 years old in a metal box and it still works fine. A unit made by Topaz uses SCR's and does zero crossing switching. Sola also makes resonator types which I prefer. They are all pretty heavy, the Sola's are extra heavy.

[paulster]

paulster, what do you do about the mains here in the UK. I'm in the process of trying to order some Heyboer trannies, however I know that our mains is supposed to be 230V, but here in my workshop it often reaches 245V. Do you order 230V or 240V PT's?

I always have Heyboer wind my transformers with dual 120V primaries and then run them in series for 240V in the UK. I then make sure I bias at a typical wall voltage (typically 245V where I am) rather than strictly at 240V.

Although we're ostensibly 230V, we haven't actually changed since the European 'harmonisation' on voltage so we still actually use 240V.

I gather some European countries have actually changed from 220V to 230V, but it's not very well publicised.