[Prev][Next][Index][Thread]

Jim's strobe was Terry's Strobe

Hi Jim,

	I picked a strobe up from the Shack today.  Mine is the RS# 42-3048
version that is in a small nice steel case and all.  No schematic but the
16 simple parts are no big deal.  I would guess that the electronics are
similar to the older 42-3009.  The case is super strong and the thing can
easily stand up to some rough use.

	The flash rate is about 10 per second (guess) so that will have to be
beefed up to 60Hz.  The electronics seems obvious.  I borrowed a high
voltage 100X probe tonight so I'll probe around in it and find the
waveforms.  Perhaps changing one of the big caps to a smaller value is all
that is needed to increase the flash rate.  It appears to be a DIAC
triggered thing, so just feeding the DIAC with the divided down AC waveform
should sync it right in.

	I tried looking at a sync gap with it in the "as bought" form and the
image is rock sharp and it almost looks like the rotor is standing still
with excellent brightness and sharpness.  There is a definite tendency for
it to lock on the 60Hz harmonics and such but it does jitter badly right now.

	I am thinking of sending the DIAC the divided down AC signal and using the
"already there" pot to adjust the voltage to just the point it fires at the
peak of the AC signal.  Should be straight forward but have to be sure not
to overstress anything.  I notice RS went all out in warnings and cautions
about playing with this "hot line" AC toy with the cover off.  Good thing I
am "qualified personnel" ;-))

This is looking very promising!!  I will probably have the schematic
reversed tonight and hopefully the mods will be easy and cheap.  If a new
cap is needed, DigiKey should cover the need.  Everything else seem perfect
for our use.  This thing seems to have just about all the nice parts as is
in a very nice package and with good quality...

We will see if Ted can squeeze any info out of RS engineering but they
probably will be tight lipped as they will not want to contribute to our
getting zapped off that 340 volts "high voltage" ;-))  But maybe they will
offer some hints...  That 1/2 amp fast fuse looks like a candidate for
"improvement" ;-)  Looks like it should turn out perfect for gap timing...

The science goes on...

Cheers,

	Terry


At 08:36 AM 03/28/2000 +0100, you wrote:
>No schematics on the one I had, although the web site may have it. 
>However, the PC board inside is so simple that reverse engineering it is
>trivial... I'll see if I can scrounge it up.
>
>----------
>> From: Tesla List <tesla-at-pupman-dot-com>
>> To: tesla-at-pupman-dot-com
>> Subject: Re: Terry's Strobe
>> Date: Tuesday, March 28, 2000 12:43 AM
>> 
>> Original Poster: Terry Fritz <twftesla-at-uswest-dot-net>
>> 
>> At 11:48 AM 03/27/2000 -0800, you wrote:
>> >The cheap Radio Shack strobe, when set to a fast flash rate, tends to
>flash
>> >in sync with the line frequency.  It's because they use a half wave
>doubler
>> >to charge the strobe cap.  It would be a simple matter to modify it so
>that
>> >it flashes exactly  in sync.
>> >
>> >
>> 
>> Hi Jim,
>> 
>> 	Hey that's a great idea!!  The Radio Shack thing (RS# 42-3009 for 34.99
>in
>> my old 1998 catalog) probably has all the basic electronics in it that we
>> need!  Perhaps a simple modification and some testing would get it to
>flash
>> at 60 or 120 Hz and insure that the flashes are at the exact peak of the
>AC
>> cycle.  Radio Shack is good about including schematics and stuff and the
>> modifications should be easy to figure out and easy for the average
>person
>> to do.  They are commonly available and the design never changes so
>anyone
>> should be able to use it.  They are always putting that stuff on sale too
>> but you never know when.
>> 
>> 	It would give bright and fast flashes that should provide excellent stop
>> action.  Just have to work out the modifications...
>> 
>> 	I ran some numbers today to convert my strobe to sharper rates and it
>> could be done but this Radio Shack thing would give so much better
>> performance it is definitely the thing to try next.
>> 
>> Another project!  ;-))
>> 
>> Cheers,
>> 
>> 	Terry
>> 
>