[sci.electronics] step up transformer

johne@ex.heurikon.com (John Eckrich) (01/24/91)

map@zeppelin.rutgers.edu (O. C.) writes:

>My brother and I are building guitar amps.  Any help with inexpensive
>sources for step up transformers(120->350)?

Use a 40V (ie. 120 -> 40) transformer, and plug it in backwards.

DigiKey has the following:

Part #		Volts		Amps		$$$
------		-----		-----		---
T107-ND		40		.110		 8.25
T117-ND		40		.250		10.68
T127-ND		40		.600		14.80


--
-------------------------------------------
johne@heurikon.heurikon.com
Madison, WI

dana@locus.com (Dana H. Myers) (01/24/91)

In article <Jan.23.03.46.07.1991.5100@zeppelin.rutgers.edu> map@zeppelin.rutgers.edu (O. C.) writes:
>
>My brother and I are building guitar amps.  Any help with inexpensive
>sources for step up transformers(120->350)?

  Step up the line voltage or impedance?

  One trick with guitar amps is to make the volume knobs go to 11, that
way, you'll have one more to go when others have already hit 10.

-- 
 * Dana H. Myers KK6JQ 		| Views expressed here are	*
 * (213) 337-5136 		| mine and do not necessarily	*
 * dana@locus.com		| reflect those of my employer	*

whit@milton.u.washington.edu (John Whitmore) (01/26/91)

In article <1228@heurikon.heurikon.com> johne@ex.heurikon.com (John Eckrich) writes:
>map@zeppelin.rutgers.edu (O. C.) writes:
>
>>My brother and I are building guitar amps.  Any help with inexpensive
>>sources for step up transformers(120->350)?

>Use a 40V (ie. 120 -> 40) transformer, and plug it in backwards.


        NO this is dangerous!  A transformer has sufficient inductance
to ensure that at its rated input voltage and frequency, current is
limited so that the transformer iron does not reach its magnetization
limit.  Above this limiting current, the transformer is a short circuit.
The 40-volt winding is lower inductance than the 120-volt winding,
thus will proabbly saturate the transformer, and burn out your
fuse (if you're lucky).

        There's lots of old vacuum tube equipment around that
used moderate amounts of current at high voltage; for that matter,
a microwave oven transformer goes from 120 to 1200 or so (some
vacuum tubes are still around...).  Look for an appropriate
unit in a disused piece of equipment... somewhere.
        Parenthetically, 120/220V transformers for voltage conversion
are relatively common; 220VAC rectifies to about 300VDC; would
that do?

        John Whitmore
                                                                        

dam@cs.glasgow.ac.uk (David Morning) (01/28/91)

In article <1228@heurikon.heurikon.com> johne@ex.heurikon.com (John Eckrich) writes:
]map@zeppelin.rutgers.edu (O. C.) writes:
]
]>My brother and I are building guitar amps.  Any help with inexpensive
]>sources for step up transformers(120->350)?

DANGER! DANGER! DANGER! DANGER! DON"T DO THIS!!! YOU'LL END UP WITH A FIRE!!
Plugging a winding designed to handle 40volts into 120volts is asking for trouble!
]
]Use a 40V (ie. 120 -> 40) transformer, and plug it in backwards.
]
]DigiKey has the following:
]
]Part #		Volts		Amps		$$$
]------		-----		-----		---
]T107-ND		40		.110		 8.25
]T117-ND		40		.250		10.68
]T127-ND		40		.600		14.80

DANGER! DANGER! DANGER! DANGER! DON"T DO THIS!!! YOU'LL END UP WITH A FIRE!!

Am I imagining things or is this newsgroup becoming more dangerous?
First it was "How to fry someone peeing in your window" and now this!

Dave