Jeff,
This looks like it'll work great! Got to rumaging around and found an old battery charger at 10 amps. Found a source for copper clad carbon rods. Have several old soldering irons. Just need to find time to put it all together.
THANKS ! ! ! !
John T.
PS: I missed the Midnight Flyer --- Miss Nell left without me
BigG wrote: Please do not couple power sources in parallel. That is a fire hazard waiting for an excuse to happen. Rewiring the centre-tapped leads of your transformer is doing exactly that. Don't knock the tubes; at least you can run them red-hot and they'll still be there tomorrow, unlike those tiny newfangled things that just go pfft!
Please do not couple power sources in parallel. That is a fire hazard waiting for an excuse to happen. Rewiring the centre-tapped leads of your transformer is doing exactly that.
Don't knock the tubes; at least you can run them red-hot and they'll still be there tomorrow, unlike those tiny newfangled things that just go pfft!
Not true if you match the phase. It's done very often with dual input voltage transformers. In fact many heathkits were wired that way.
The mind is like a parachute. It works better when it's open. www.stremy.net
Jeff, thanks for the link! Looks like the easiest way to go!
Chuck, thanks for making it clickable.
Now that I've beat vaccumn tubes to death, can someone point me to a good source for buggy whips? I need to flog these nags so I can get to the station to meet Miss Nell on the Midnight Flyer
John T
jawnt wrote:It has been so long since I had any power supply therory, I need helpI have plans for a Resistance Soldering rig that calls for a 6.3 volt 6 or 7 amp filament transformer. Anyone tried to find one of those lately?What I'm wondering --- Can I take a 12.3 v center tapped transformer at 3.5 amp and tie the outside legs together and use them with the center tap and get my 6 volts at 6 amps or so?Been too many years since vacumn tubes John T.
It has been so long since I had any power supply therory, I need help
I have plans for a Resistance Soldering rig that calls for a 6.3 volt 6 or 7 amp filament transformer. Anyone tried to find one of those lately?
What I'm wondering --- Can I take a 12.3 v center tapped transformer at 3.5 amp and tie the outside legs together and use them with the center tap and get my 6 volts at 6 amps or so?
Been too many years since vacumn tubes
jbinkley60 wrote: jawnt wrote: THANKS guys!!Already I like this new forum! See what happens with senior moments? Tie the 2 output legs together ---- of course it'll create a dead short ---- like the one between my earphones Chuck, Karl, vacumn tubes are those little glass thingys the just barely glow it the dark. John T.Vacuum tubes - a discussion on grid dip oscillators is just around the corner.
jawnt wrote: THANKS guys!!Already I like this new forum! See what happens with senior moments? Tie the 2 output legs together ---- of course it'll create a dead short ---- like the one between my earphones Chuck, Karl, vacumn tubes are those little glass thingys the just barely glow it the dark. John T.
THANKS guys!!
Already I like this new forum!
See what happens with senior moments? Tie the 2 output legs together ---- of course it'll create a dead short ---- like the one between my earphones
Chuck, Karl, vacumn tubes are those little glass thingys the just barely glow it the dark.
Vacuum tubes - a discussion on grid dip oscillators is just around the corner.
Sad to say I was at NASA in Greenbelt Maryland about 12 years ago. They were using tubes for their voltmeter with a layered VFD number display! I had to hit the thing on the side after it warmed up to get it to work!
I spoke to John G, a fellow MRR' who also worked at NASA. He loved those things!
<shivers>
Don - Specializing in layout DC->DCC conversions
Modeling C&O transition era and steel industries There's Nothing Like Big Steam!
Now just a minute, young whippersnapper! I well remember that the first thing my high school electronics instructor told me to get was my own copy of a tube manual! (Up 'til then I had been borrowing his.) I also remember table radios that were suitable subs for electric space heaters - and drew nearly as much power. Not to mention 12.6V CT filament transformers that weighed as much as small boat anchors.
Then along came miniaturization, reduced power requirements, integrated circuits that draw less power than a pencil flashlight bulb... One price we pay is the loss of availability of those huge, high-power transformers. Ain't progress wonderful?
(Have you priced horseshoes lately?)
Chuck (modeling Central Japan in September, 1964 - from data collected on-site)
Engineer Jeff NS Nut Visit my layout at: http://www.thebinks.com/trains/
jawnt wrote: It has been so long since I had any power supply therory, I need helpI have plans for a Resistance Soldering rig that calls for a 6.3 volt 6 or 7 amp filament transformer. Anyone tried to find one of those lately?What I'm wondering --- Can I take a 12.3 v center tapped transformer at 3.5 amp and tie the outside legs together and use them with the center tap and get my 6 volts at 6 amps or so?Been too many years since vacumn tubes John T.
You can't tie them together because that would create a dead short across the transformer. You can use two diodes and create a full wave (1/2 of a full wave bridge) recitifer and get 6V at 6A. It will be recitified DC as opposed to AC. Depending upon the full circuit this may work. If you have current limiting via the resistance soldering you might be OK without worrying about burning out the diodes but large current spikes through diodes might not be handled well. Seeing the full circuit would help.
Texas Zepher wrote: jawnt wrote:Can I take a 12.3 v center tapped transformer at 3.5 amp and tie the outside legs together and use them with the center tap and get my 6 volts at 6 amps or so?I think you would get a 12.3V short circuit and rapidly melt down the transformer.
jawnt wrote:Can I take a 12.3 v center tapped transformer at 3.5 amp and tie the outside legs together and use them with the center tap and get my 6 volts at 6 amps or so?
Connecting the end legs directly would yield a direct short, and some interesting (and possibly expensive) smoke effects.
OTOH, connecting the ends through opposed diodes would give alternating half-waves. Unfortunately, that still won't generate 7A at 6.3(minus diode drop)V.
The heaviest 12.6V center-tap transformer in my supplier's catalog is only 5 amp capacity. If you put its 12.6V output through a 2/1 stepdown transformer, you would end up with 10A at 6.3V - but the least expensive (100W) stepdown transformer costs a lot more than the filament transformer!
I guess this is the price we pay for miniaturized, low-power electronics.
Chuck (modeling Central Japan in September, 1964)
rolleiman wrote: This may help you achieve the cheap goal of resistance soldering and probably be a little safer than fooling around with the coils of a transformer.. http://www.rolleiman.com/help/solderer.pdf (500K file)Good luck..
This may help you achieve the cheap goal of resistance soldering and probably be a little safer than fooling around with the coils of a transformer..
http://www.rolleiman.com/help/solderer.pdf
(500K file)
Good luck..
Just making the link clickable.
http://www.rolleiman.com/help/solderer.pdf (500K file)
Not directly, since the ends are out of phase. What you might be able to do is this:
1) Gently open the paper/plastic covering to expose the center tap wire.
2) See if it comes from two seperate pieces of magnet wire. That is, a center tapped transformer is sometimes actually two secondary windings with a common lead.
3) IF so, then seperate the two center leads, use an ohmmeter to find which winding is which.
4) Now wire the windings in parallel top to top and bottom to bottom.
5) Apply power through a small fuse (1 amp or so). If it blows then the phase is reversed. Swap one set of leads. If it doesn't blow than you are golden.
6) Monitor it carefully for the first hour or so. It the windings are for some reason not nearly identical there will be some current flow between them and the transformer will heat up. That's a bad thing.
Best of luck.
Karl
PS: What's a vacuum tube? Only kidding, I cut my electronics teeth on them. I still repair or tweek the occasional audiophile (or guitar) amplifier. Can you say mellow? Love that odd order harmonic content.