Does Someone Make Transformers Here?

[sp10mk11]

Hello
I have a bought US Pioneer tape deck, it has a 120volt transformer fitted, I would like rather than run it off an auto transformer to fit a 220v primary and two secondaries of 24 volt and 14 volt transformer
The unit consumes a maximum of 25 watts when run on 120v ac, and I assume this is a peak figure when the solenoid kicks in.
Can anyone help
Thanks
Gary

[mole42uk]

You need Ed Dinning

[mark_in_manc]

I have some 120-0-120 primary, 24-0-24 sec small torroids. If you could fiddle one of the secondaries for 14v with a Vreg, perhaps this would do you?

[Ed_Dinning]

Hi Gary, it is normally possible to buy a 240 to 120 transformer in many outlets.
However, as it is a tape deck it may well have an AC drive motor fitted that will depend on the mains frequency for its speed of rotation. It would there for run slow if it were to be connected to the correct voltage at 50Hz when it should be on 60Hz.
That said, if it is an electronically controlled motor it could run satisfactorily on the UK 50Hz supply if supplied with the correct voltage. This type of device sometines has a multi tapped transformer inside the cabinet where the tapping can be reset to the local mains voltage. Have a check for that and get back to us.

Ed

[David G4EBT]

Is there any reason why one of the standard 240/120V adaptors wouln't fit the bill?:

http://www.yourspares.co.uk/parts/ys...FQcQ0wodiVAJvA

[julie_m]

The original transformer may not have enough steel in it to cope with 50 cycle mains. If the core has been designed for a half-period of 8.333 ms, it might reach saturation during the extra 1.667 ms. And the beancounters in charge are going to be more concerned with their profit margins than a 20% margin of safety.

A cassette deck most probably will be using a DC motor, so not be dependent on the mains frequency. A reel-to-reel deck with an AC motor will run slow in the UK. (But if it has the option to select 50 or 60 cycles, then that suggests that the transformer will tolerate the lower frequency.)

[sp10mk11]

Hello all
Thanks for your replies, I did check the transformer to see if it has any additional taps but the only extra one is for 100v AC.
The motor is indeed a DC Servo Control one so mains frequency will not affect it.
I have been running it off a step down transformer but would rather try and obtain a 220-24/14 v one I could fit inside the unit.
I have been through all my transformers that I have collected over the years but not one with these voltages on it
Gary

Mark thanks for offer of the toroidals.

[Skywave]

Gary - you have a P.M.

Al.

[sp10mk11]

Just thought I would upload a picture of the 120V transformer, it actually has 3 outputs, Red 20v AC, Brown 14v AC and small set of blues next to the primary wires are also 14v Ac this winding illuminates two 250ma fuse bulbs when in record mode.
Did I mention that this is an 8 track recorder

Gary

[sp10mk11]

Here is the circuit that it drives.

[TonyDuell]

Since that diagram says 120V 50-60Hz by the mains plug, it would suggest to me that the transformer does have enough iron to be OK on 50Hz. It probably could be rewound for UK usage but it may be cheaper just to use an external autotransformer.

Since there doesn't seem to be an AC motor (and since the circuit says 50-60Hz), I think the tape speed will be unchanged.

As an aside, I have a Panasonic 8-track cartridge recorder which is designed for 120V 50-60Hz mains. It has a DC motor and runs fine off a step-down transformer in the UK.

[sp10mk11]

Hello Tony
Yes I have been using a step down transformer but I would like to get a 220v transformer that I can fit inside and do away with the stepdown transformer.
It uses a DC servo control motor so no problems with different line frequencies.
Gary

[Ed_Dinning]

Hi Gary, not sure of the space you have inside the set, but the existing transformer could be rewound for a 240v primary or it could be reverse engineered and a new (probably slightly larger) transformer made up with a 240v pri to replace it.

Ed

[turretslug]

It's difficult to tell for sure, but the fact that both secondaries have the same type of rectifier and a 1000uF (1mF) reservoir implies that the current from each is at least of similar order. I wonder if a standard 25VA transformer with 2x 24V secondaries would suit here if the appropriate number of turns was removed from one secondary? A modern, split bobbin type often has accessible secondary end connections on solder tags and easily un-wound turns, the appropriate number of turns could be removed from the one with easier access, un-weaving it from around the stack half a turn at a time. Measuring the initial secondary voltage (and the primary side input), removing say ten turns and re-measuring the secondary output (having re-checked primary side, as a bit of time will have elapsed and a well-known law says that everyone in the street will have put the kettle on in the meantime....) and a bit of maths will give a turns-per-volt figure to get down to 14V.

If anyone can see a flaw in this reasoning, please tell!

[Nymrod121]

Originally Posted by mark_in_manc

I have some 120-0-120 primary, 24-0-24 sec small torroids. If you could fiddle one of the secondaries for 14v with a Vreg, perhaps this would do you?

Evening Mark - PM sent ...
Cheers
Guy

[Diabolical Artificer]

I might have a suitable tfmr int shed, will look.

Andy.

[sp10mk11]

Thanks again for replies
ED
I do have a bit space to play with, do you mean stripping this transformer?
Gary

[sp10mk11]

Err I made a discovery in another box!

This was a 50 watt stepdown transformer............so I hacksawed the casing open and a small neat 220-110 transformer was in it, I tried it and it runs the 8 track without getting hot, so I found a case for it and have mounted it as you see, it is a little bit hummy so I have used some mumetal.

All I can say is massive thanks to all of you who gave advice, time and effort, I am prone to forgetting what I have already and often order stuff I do not need (pathetic excuse I know)...............Ducks to avoid barrage of flying transformers!

Gary

[Skywave]

The important thing is that you have solved your problem.

As for keeping track of what you have, (or don't), if you have a substantial collection of salvaged mains transformers (such as I have) - or almost anything else, come to that, such as valves - it is worthwhile making an Excel spreadsheet listing them by a self-allocated serial number or their common name with a brief spec. of the data about said items and how many of each you have. Yes, I do realise that doing that does take some considerable time and effort, but once done, it's done, except for amending that database as required, of course. Personally, I view doing such a database build (and it's upkeep) as an investment in my time:

"I need an XYZ that will do so-and-so. But have I got one? Let's have a look at the database".
"Ah-ha! There's one! Looks like that will do nicely."

So into the stores - and fetch it: nice 'n' easy; no head-scratching; no poking around.

Al.

[Andrew B]

I just like them transformers that have the primary wound on a separate bobbin, I leave the primary bobbin alone and rewind the secondaries, I cheat and use a lathe with a "clikstick" to count the turns.