[ARC5] [Milsurplus] Sandy Coolness for Our BAs

Sat May 13 09:35:26 EDT 2017

Rather than an additional analog power supply, how about a SMPS or one of those small flyback type regulators that can make 12 0r 24 V into 135V or 250V or whatever you design it to do?Tom Hanz had the "replacement armature " concept that replaced the rotating armature in the dyno with a smps board that made contact with the brushes. A Very cool idea to keep the original look. 
I had considered building a flyback  supply inside a small box with bananna jacks to inerface with the radio .These have OC and OV shudowns and WILL survive a screwdriver !

    On Saturday, May 13, 2017 2:40 AM, Tom Lee <tomlee at ee.stanford.edu> wrote:

  The ones I've encountered in the past were very good at exploding during an unscheduled screwdriver test, so Dennis has an excellent point. These are very simple regulators, so their short-circuit protection consists of instructions to the user not to short it.

 --Cheers,
 Tom
 -- 
Prof. Thomas H. Lee
Allen Bldg., CIS-205
420 Via Palou Mall
Stanford University
Stanford, CA 94305-4070
http://www-smirc.stanford.edu
650-725-3383 (public fax; no confidential information, please)  On 5/12/2017 11:25 PM, Dennis Monticelli wrote:

 The one transistor NPN control device probably just has a zener between its emitter and ground.  A resistor divider across the output has its tap connected to the base of that NPN. 
  I don't know what the SOA of that Darlington is or if there is another NPN in there serving as a current limit.  In other words it may not survive a screwdriver short so beware.  

  Dennis AE6C   
 On Fri, May 12, 2017 at 10:15 PM, David Stinson <arc5 at ix.netcom.com> wrote:

----- Original Message ----- From: "Tom Lee" <tomlee at ee.stanford.edu>
 Subject: Re: [ARC5] [Milsurplus] Sandy Coolness for Our BAs

 If this part is like some of the TV regulators I've encountered in the
 past, the base terminal needs to be pulled up to the unregulated input
 voltage through a resistor. Depending on the input-output differential
 you seek, the resistor will be of the order of 10k or so, typically.
 Frequency compensation is also frequently required, and the base
 terminal is a convenient place to connect an appropriate stabilization
 network (e.g., C or series RC to ground).

 Mr. Tom Lee was exactly correct.
 Many thanks also to Bob AH7I, and
 John Kidd from Australia for more info
 and details.
 10 K from INPUT to BIAS, .1 uFd
 from BIAS to COMMON and 10 uFd on
 the OUTPUT, similar to what one would do
 with a common low-V regulator.
 The isolation transformer, bridge and
 47 mFd filter is supplying ripply 180V
 peak to the regulator device.
 A nice, clean and steady 135V is
 running the receiver.

 Gentlemen like you continue to prove
 that my confidence in our community
 is well-founded.

 TNX OM ES 73 DE Dave AB5S

 ----- Original Message ----- From: "Tom Lee" <tomlee at ee.stanford.edu>
 Subject: Re: [ARC5] [Milsurplus] Sandy Coolness for Our BAs

 If this part is like some of the TV regulators I've encountered in the
 past, the base terminal needs to be pulled up to the unregulated input
 voltage through a resistor. Depending on the input-output differential
 you seek, the resistor will be of the order of 10k or so, typically.
 Frequency compensation is also frequently required, and the base
 terminal is a convenient place to connect an appropriate stabilization
 network (e.g., C or series RC to ground).

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