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- To: <tesla-at-pupman-dot-com>
- Subject: H & R Transformers
- From: "Thomas McGahee" <tom_mcgahee-at-sigmais-dot-com>
- Date: Tue, 11 Mar 1997 21:12:46 -0500
Fellow Coilers, To answer some of the questions that people have asked concerning the H & R Transformers: Each transformer is rated at 5KV at 300ma. Primary is 110/120 VAC 60HZ. (note that since two transformers would normally be used, you can wire the primaries in parallel for 110 or in series for 220 VAC operation) The core is quite massive, and I believe you could run these at 50Hz, although you might have to de-rate them a little. Not having access to 50Hz I cannot vouch for 50Hz operation, but hopefully someone out there with 50Hz will buy a couple and get back to the rest of us and tell us if they run OK at european frequencies. The physical size of each transformer is 6" tall x 7" core length x 6" wide. They are heavy duty construction with angle brackets for mounting. The quality of construction is excellent. The primary is located at the physical top of the core. The primary is about one inch thick and extends outward for about 6 inches. It is not round, but somewhat oval shaped, like a racetrack. Connections are made with large quick-connect terminals. Below the primary there are two magnetic shunts installed between the primary and the secondary, one on either side. These are in the form of a block of laminated core material and some form of insulatory material wrapped around the block. I have not tried to remove the shunts, but it looks like it would only require some gentle tapping with a rod and hammer to loosen them. I like the shunts being there, because it does allow you to use it for a Jacob's ladder, and eliminates the need for extra primary inductance to limit current. The secondary occupies the bulk of the transformer. I do not know what the wire size is, as I have not disassembled one, and do not plan to either. At the base of the secondary are three quick connect terminals. These appear to be part of a resonant winding that a supplied AC capacitor can be connected to. I believe this was used to help regulate the secondary voltage. You can operate the transformer with or without the AC capacitor connected. I am not exactly sure whether the AC capacitor and the base winding are part of a power factor correction scheme or a resonant regulator scheme. Each person will have to experiment and determine whether they want to use or ignore this aspect of the transformer. Someone questioned whether the transformer was rated for continuous duty. When I originally ordered my unit the H&R people told me that it was a unit from some sort of copy machine, and that it was continuous duty. This sucker is built *solid*. It sure as heck looks like it is built for continuous duty. I have not personally run it for a full year at rated load, so I will not make any claims beyond repeating what I was told. Now, I honestly don't know what kind of copy machine would need such a brute transformer for its high voltage section, as all the copy machines I have ever torn apart never had anything as humongous as *this* baby inside. In fact, the transformer weighs more than most of the copiers I have lifted! As to its usefulness in a Tesla Coil, I am appending the following post that appeared here on the Tesla list. It was a response to Malcolm Watts' call for coil info. You will note that Barry Benson's Tesla coil uses two Transformers that appear to be the same ones that H&R is selling. Maybe Barry can give us some more intimate details of how well these transformers work, and if there are any things about them that we should know. ---------- Benson_Barry%PAX5-at-mr.nawcad.navy.mil From: "tesla"-at-poodle.pupman-dot-com-at-PMDF-at-PAXMB1 To: Benson Barry; "Tesla-list-subscribers"-at-poodle.pupman-dot-com-at-PMDF-at-PAXMB1 Subject: Coil Research Date: Tuesday, February 11, 1997 2:02AM -snip- Secondary Height=27" Diameter=6" Turns=~630 Wire diameter=#18 gauge (.0421") Top terminal Type, Size=toroid, 5 high X 20"diameter Resonant Frequency with terminal=~200khz Q without terminal (optional)=haven't measured Q with terminal (optional)="""""" Primary cap value=.04 Peak primary cap voltage=14kv (2 5kv photocopier transformers in series x 1.414) Breaks per sec=14 X 1750 / 60 = 408 Output length to grounded rod=56" -end snip- Barry reported a 56" spark length using a 6" diameter by 27" secondary using 2 5kv photocopier transformers in series. So, obviously the transformers do a pretty good job in Tesla service. I am hoping that Barry will see this post and give us any useful details that he can on the merits of these transformers, and any special details about using them that he may have learned along the way. Anyone else out there used these transformers? My purpose in alerting the members of the list to this transformer is to share with you what I consider a great find. I bought two myself. I figure if $20 for a 12KV 30ma neon transformer is considered good, and if that is only 360 watts, then it would take about 8 of these $20 neons to equal the power you can get with just two of the H&R units. $180 worth of neons versus $100 worth of H&R transformer. You have to *see* these units to appreciate how beautiful they are! Someone asked if the 100 in stock that I mentioned was all they would ever have. I don't know. But I tell you this: If we coilers bought up their entire stock over the next week or so, you can be sure they would keep their eyes out for MORE! These items have probably *not* been their biggest selling item, because it is not the kind of thing everybody needs or wants. But it is *exactly* the kind of thing we coilers can use. How many of you coilers and would-be coilers were unaware that such a transformer existed? Or if you knew it existed, how many of you were hesitant to buy one or two because you did't know if it was going to be useful in Tesla service? I hope that the info I have gathered about this transformer helps many of you to finally get a decent power source for your Tesla coil. Does anyone else out there have info about any other such bargains that we could all take advantage of? Fr. Tom McGahee *** here is the original post, in case you missed it or misplaced it *** Fellow Coilers, Yes, 10KV RMS -at- 300ma for less than $100 delivered in the USA. I have run across a transformer that is just about perfect for Tesla Coil work, and I want to let you all in on it. Herbach and Rademan have 100 of these transformers in stock. They are rated at 5,000 volts RMS, 300 ma continuous duty. These are *open-frame* transformers, absolutely NO tar or anything else to give you problems. Mine came with power factor correction capacitors included. There are current shunts installed... which is actually a *plus*, because it means you do not need any reactance added to the primary! If you insist on removing the shunts, it is very easy to do so, since it is all open frame construction! The secondary is entirely isolated from the core! I bought two of these and wired the primaries in anti-parallel. This makes the phase of the two secondaries *opposite*. That allows me to take the inner wires of each secondary and wire them together so that the two *outer* wires of the secondaries are oppositely phased. In other words, the total series output is now 10,000 volts AC RMS (14KV Peak!) at 300 ma. If desired, the inner wires of the secondaries can be connected to AC ground, so that the electrical stresses are reduced. But if you want to, you can also leave them floating. Both ways work. Buy two for $39.50 each, throw in about $15 for shipping, and you are under $100 for an almost perfect 10KV RMS 300ma *open frame* NO TAR transformer for your Tesla coil. The really daring among you can figure out other combinations of these transformers, I am sure. Part Number TM92XFR2019 5KV 300ma Transformer $39.50 each Herbach and Rademan 18 Canal St. P.O. Box 122 Bristol, PA 19007-0122 Orders 1-800-848-8001 Fax 215-788-9577 Business hours Mon-Fri 8 am - 5pm EST Ask to be placed on their mailing list! Hope that this is something useful for all of you. This is not exactly a pole pig, but two of these will deliver 3,000 VA at continuous duty. Not bad! Fr. Tom McGahee
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