Forums :: Resources :: Features :: Photo Gallery :: Vintage Radio Shows :: Archives :: Books
Support This Site: Contributors :: Advertise


It is currently Jun Mon 18, 2018 6:07 pm


All times are UTC [ DST ]





Post New Topic Post Reply  [ 14 posts ] 
Author Message
 Post subject: My all new isolation trans./variac
PostPosted: Feb Mon 26, 2018 4:05 pm 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 2205
Location: Spring Hill, FL
I present to you my latest creation - the Isovac 3000B. It's an isolation transformer and variac all in one (hence the name Isovac). Model number 3000, just because, and B because it's replacement for the original Isovac 3000 that I made about 10 years ago. I had a couple improvements in mind, and turns out it was better to just start from scratch. And I know that there was a fierce debate over whether or not to ground the output. I'm with the crowd that says no, so it does have a 3 prong outlet, but the ground slot is not connected. But that way I can still work on amps that have a 3 prong cord.

I am going to change out the voltage scale since it's only to 120, not 130.

Image

Image

Image

_________________
Michael


Top
 Profile  
 
 Post subject: Re: My all new isolation trans./variac
PostPosted: Feb Mon 26, 2018 5:37 pm 
Member
User avatar

Joined: Jul Mon 26, 2010 8:30 pm
Posts: 22308
Location: Annapolis, MD
Nice!!---what is the case?

_________________
-Mark http://pixellany.com

"It's always something". --Gilda Radner (1946 - 1989)


Top
 Profile  
 
 Post subject: Re: My all new isolation trans./variac
PostPosted: Feb Mon 26, 2018 7:12 pm 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 4175
Location: Charleston, W.Va.
Hi Michael,
Congratulations! That is a very nice piece of work. 8)

I am in full agreement with you on your decision not to ground the outlet. By no means should this be done if this also serves as an isolation transformer. But using the 3-prong receptacle (equipment ground slot not connected) permits convenient connection of any gear, no matter whether it has a 2-prong or a 3-prong line cord. I have exactly the same setup on my own custom enclosure. [Although I will be the first to admit that mine does not have nearly the professional-looking appearance as yours.]

_________________
Poston


Top
 Profile  
 
 Post subject: Re: My all new isolation trans./variac
PostPosted: Feb Mon 26, 2018 7:51 pm 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 852
Location: Wayside, NJ Monmouth
I have to disagree with Poston Drake . If your were to purchase a new Stand alone Isolation transformer, it would be equipped with a Three wire Power cord. The ground wire would pass through and be there for a Safety Ground. If your working on an All American Five, which would have a Two Prong Power Cord there would be no connection to the Safety Ground. But if you were to work on something that has a three wire power cord the isolation transformer would work just the same. But is something was to short to Chassis / Earth gourd the current would be bleed of and any safety ( fuse or Breaker) work trip. The ground wire is there for a reason.


Top
 Profile  
 
 Post subject: Re: My all new isolation trans./variac
PostPosted: Feb Mon 26, 2018 9:12 pm 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 2205
Location: Spring Hill, FL
N2LXM wrote:
If your were to purchase a new Stand alone Isolation transformer, it would be equipped with a Three wire Power cord.


Not always. You are looking at one that didn't. It came from Jameco, and I took the transformer case apart to remove the line cord (which is two pronged and was reused here), as well as the outlet, which was also two pronged.

What you have to keep in mind is that ground is an alternative path for the neutral line. But this is an isolation transformer. Current flows out of one side of the transformer secondary, through the device then back to the other secondary lead. An alternate path back to the line side would not complete any alternate path. So if you were in any way grounded and touch a hot lead in the device, it won't shock you because there is no complete circuit path.

_________________
Michael


Last edited by TPAairman on Feb Mon 26, 2018 9:17 pm, edited 1 time in total.

Top
 Profile  
 
 Post subject: Re: My all new isolation trans./variac
PostPosted: Feb Mon 26, 2018 9:14 pm 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 2205
Location: Spring Hill, FL
pixellany wrote:
Nice!!---what is the case?


This isn't the same size, but one like this: https://www.amazon.com/uxcell-Metal-Enclosure-Project-Junction/dp/B00LGJ2SEU/ref=sr_1_17?ie=UTF8&qid=1519676031&sr=8-17&keywords=project+enclosure

I then painted it black and off white. I have to say that overall it isn't bad, but I'm not impressed with the tiny screws that hold the front and back panels on. There really isn't enough grab for my liking. A trip to Lowes is in the future on that point.

_________________
Michael


Top
 Profile  
 
 Post subject: Re: My all new isolation trans./variac
PostPosted: Feb Mon 26, 2018 10:14 pm 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 32666
Location: Maryland 20709, USA
Nice job, Michael.

- Leigh

_________________
73 de W3NLB
http://www.AtwaterKent.info
Click "Grebe Stuff" for Synchrophase info


Top
 Profile  
 
 Post subject: Re: My all new isolation trans./variac
PostPosted: Feb Tue 27, 2018 9:41 pm 
Member

Joined: Dec Thu 10, 2015 7:01 pm
Posts: 203
Location: Aurora, IL
I like it! And since you can never get too many kudos... nice job!


Top
 Profile  
 
 Post subject: Re: My all new isolation trans./variac
PostPosted: Mar Sat 03, 2018 3:17 am 
Member

Joined: Jul Thu 29, 2010 5:35 am
Posts: 943
Location: Simonton, Texas
Looks great and practical too.

My home brew projects almost always looked kluged together because I am always in a hurry when

I am building them. One of these days I m going to take my time and build a nice one.

_________________
Knowledge is useless unless you can share it. KA5OBI


Top
 Profile  
 
 Post subject: Re: My all new isolation trans./variac
PostPosted: Mar Sat 03, 2018 12:41 pm 
Member

Joined: Oct Sun 15, 2006 12:57 pm
Posts: 5622
Location: Liberty, Missorui
Impressive, nicely done, good looking cabinet choice, and great graphics. You've got my vote.

Nice to see you leave ground where it belongs, on the other side of the transformer. Yes, real two wire isolation transformers are still sold, but you have to look a little to find them, amongst all the modern "noise isolaters".

_________________
Pics, Bold & underlined text, are usually links.

https://mikeharrison.smugmug.com/

Mike


Top
 Profile  
 
 Post subject: Re: My all new isolation trans./variac
PostPosted: Mar Tue 06, 2018 3:54 am 
Member
User avatar

Joined: Jan Sun 15, 2012 4:20 pm
Posts: 543
Location: Lawton Oklahoma
Beautiful work sir!

I have a couple BK Precision 1655 and was looking at the schematics they have all sockets at Isolation, soldering Iron output, and input chassis grounded. Is this BK a different animal entirely?


Top
 Profile  
 
 Post subject: Re: My all new isolation trans./variac
PostPosted: Mar Tue 06, 2018 8:22 am 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 2205
Location: Spring Hill, FL
fordtech wrote:
Is this BK a different animal entirely?


Not really. The BK just has more bells and whistles.

_________________
Michael


Top
 Profile  
 
 Post subject: Re: My all new isolation trans./variac
PostPosted: Mar Tue 06, 2018 10:14 am 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 22687
Location: Haledon, NJ, usa
Looks very nice.
No voltmeter? ...only amps?

_________________
To be a man, Be a non-conformist, Nothing's sacred as the integrity of your own mind.
-Emerson


Top
 Profile  
 
 Post subject: Re: My all new isolation trans./variac
PostPosted: Mar Tue 06, 2018 10:27 pm 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 2205
Location: Spring Hill, FL
Pbpix wrote:
Looks very nice.
No voltmeter? ...only amps?


I tried, but finding a matching set of volt and ammeters is like pulling teeth, especially ones that would fit on the panel.

I did find a pair of digital ones but there were lots of bad reviews on them. They'd just stop working, or the accuracy would just stray off.

_________________
Michael


Top
 Profile  
 
Post New Topic Post Reply  [ 14 posts ] 

All times are UTC [ DST ]


Who is online

Users browsing this forum: Barry H Bennett and 16 guests



Search for:
Jump to:  
























Privacy Policy :: Powered by phpBB