I can't get through either.? anyone able to check with stan for details?
it would be a shame to lose that content.
-walter
--
Walter Shawlee 2
Sphere Research Corp. 3394 Sunnyside Rd.
West Kelowna, BC, V1Z 2V4 CANADA
Phone: +1 (250-769-1834 -:-
We're all in one boat, no matter how it looks to you. (WS2)
All you need is love. (John Lennon)
But, that doesn't mean other things don't come in handy. (WS2)
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Having a resistor R in series with the back emf diode means:
? - the peak reverse voltage is higher: not ~0.6 but ~0.6+IR
??? where I is the relay's on current
? - the current falls faster, since the energy is dissipated in R
??? as well as the diode
Having two diodes will have a similar effect, since the 0.6 will
become 1.2.
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On 03/08/18 14:09, Chuck Harris wrote: I did a little study on back emf diodes for relays back when I
was a young engineer, and had noticed how a relay with a back
emf diode was quick to acuate, but slow to release... thus
subjecting the contact to burning on release.
I found that simply adding a second silicon diode in series
was usually sufficient to provided a nice snappy release.
Whether one or two diodes works optimally depends on the
voltage applied, and the inductance and resistance, of the relay
coil. A relay that is very sensitive, could take several seconds
to release with a single silicon back emf diode.
In some cases, better is to use a snubber where you can custom
design the release time to fit the relay, and its application.
That little self inflicted study made the equation that every
EE memorizes in school:
V(t) = L di/dt
very real for me.
-Chuck Harris
G?ran Krusell wrote:
I once read somewhere that one of the major relay vendors, don¡¯t remember which, suggests that a 10 V zener diode is inserted in series with the fly back diode. The purpose is to make certain that the relay for sure changes state.
G?ran
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I did a little study on back emf diodes for relays back when I
was a young engineer, and had noticed how a relay with a back
emf diode was quick to acuate, but slow to release... thus
subjecting the contact to burning on release.
I found that simply adding a second silicon diode in series
was usually sufficient to provided a nice snappy release.
Whether one or two diodes works optimally depends on the
voltage applied, and the inductance and resistance, of the relay
coil. A relay that is very sensitive, could take several seconds
to release with a single silicon back emf diode.
In some cases, better is to use a snubber where you can custom
design the release time to fit the relay, and its application.
That little self inflicted study made the equation that every
EE memorizes in school:
V(t) = L di/dt
very real for me.
-Chuck Harris
G?ran Krusell wrote:
toggle quoted message
Show quoted text
I once read somewhere that one of the major relay vendors, don¡¯t remember which, suggests that a 10 V zener diode is inserted in series with the fly back diode. The purpose is to make certain that the relay for sure changes state.
G?ran
|
I once read somewhere that one of the major relay vendors, don¡¯t remember which, suggests that a 10 V zener diode is inserted in series with the fly back diode. The purpose is to make certain that the relay for sure changes state.
G?ran
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His IP address was 50.246.236.85 which is pointed to by the domain "reprise.com". It is a standard Comcast address. "ping", "ftp" or a website (http) are not currently active at that address. Lyle On Thu, 02 Aug 2018 21:33:29 -0700 "penguin2004au" <clansman2011@...> wrote: I have been unable to access this site for some time. Does anybody
know what has happened? John Foster
-- 73 NM6Y Bickley Consulting West Inc. "Black holes are where God is dividing by zero"
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I have been unable to access this site for some time. Does anybody know what has happened?
John Foster
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I have a question about the A5 trigger generator sweep logic board differences. I have two 466's with out the DM44 with the same trigger board 670-3324-00 boards. I have a 464 with a DM44 with the 670-3324-01 board and it is vastly different from the 466 boards. All the DC voltage traces from J-6 are disconnected all the through holes are unsoldered so there is no interconnection from top to bottom through out the board. There appears to be no cable connection to the board from the DM44 to supply these?
The DM44 manual parts list's don't show that part number used for the 464/466 with the DM44 it shows the later 466 board and I can not find the optional boards listed in the service manuals listed in the DM44 one.
The installation sheets for installing the DM44's don't list different or optional boards used like the service manuals do?
So whats up with this bunch of missing info here!
Jim O
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There are millions if not billions on DC coil relays in the wild with integral back-emf diodes working just fine. There are certainly design misuse situations that can cause field failures. That should not indict the relay diode in any way.
Kevin
Sent from kjo iPhone
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Re: 3D Printing / Milling Tektronix parts
I think it worth pointing out that injection molding knobs would not be that difficult or expensive to set up for small production. It requires a heating chamber, a mold and a lever actuated pump. That arrangement would be slow unless you had multiple molds and could interchange them while they cooled. But if you're making 2 of this and 3 of that at a time it should be OK. Going faster gets complicated because of the need to heat and cool the molds.
The molds can be made by using silicone mold mastic to make a copy of the desired part, making a plaster copy, drying it and then casting zinc alloy pieces for the mold. This is a common technique in prototype fabrication and for jewelry production, although that often involves investment casting.
If you want more information contact me directly.
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I have never played with a 556, so I don't know the specifics..but assume
you have checked/replaced the caps where necessary.
regards
Rajesh
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On Thu, Aug 2, 2018 at 6:27 AM, <thespin@...> wrote: Apologies... two missing details... I couldn't see any obvious damage
under the HV cover, (no charring or whatever), and I don't clearly remember
if it's +100 volts or -100 volts that I measured on the -1850 supply for
the lower beam.
--
/Rajesh
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Oops I missed the plastic skirt detail... that complicates things a bit. I think I could replicate this as well... I'd print this in clear resin and then polish it, or potentially turn it out of acrylic or lexan. I'd then apply water-slide decals on the back, printed on an ALPS printer or the like, and then mask the tan from the grey section, airbrush the grey, remove the mask, airbrush the tan, and glue the skirt in place with CA glue.
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I've gotten reasonably good at 3D printing tektronix knobs. I 3D scan the original and use this as a reference in CAD. I then print the knob on a resin-based 3D printer, and airbrush the final color on, and finish with a clearcoat.
is one I did a long while back. I've since managed to get the color much closer and the finish much nicer.
I've come to believe that this method is likely not the right way to do this and that casting a new knob out of urethane would be much better... but for cracked knobs, this is probably the best.
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Hi Tam,
I was musing about replicating them more than seeking replacement knobs. I am in need of knobs for some restoration projects but they are months (or even years) away from starting.
Thanks all the same,
John
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Apologies... two missing details... I couldn't see any obvious damage under the HV cover, (no charring or whatever), and I don't clearly remember if it's +100 volts or -100 volts that I measured on the -1850 supply for the lower beam.
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Hey all,
I just acquired a 556, but it's having some fairly serious issues. Before powering it on, I checked all the supply rails for shorts with a meter, and checked the power plug for shorts as well. I then proceeded to slowly turn the scope on with a variac. Once at full voltage for a few moments, I heard a bang and smelled that something had gone wrong. Surprisingly, the main rails are all healthy (350,225,100,-150). The high voltage on the upper beam is at it's nominal voltage, but the high voltage on the lower beam is around 100 volts. Boooo.
Okay... so now I wonder... if the post-deflection acceleration (supplied by the lower beam supply only) is dead, will the CRT still light? What are the chances that I blew up the HV transformer itself and will need to wind a new one? What components are most likely to have exploded in that area?
Evan
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I would say go with the X/Y capacitors and pick ones that have the highest AC and DC voltages you can find which will fit physically. Be aware of any special local and national electric codes for equipment where you live and try to comply with the latest standards where you can. There is more to snubber applications than one might think at first. The encapsulation materials used are important from the aspect of fire and smoke hazards. The same is true for AC power switch assemblies in electronic equipment. Older models may have materials that do not meet more modern standards, but of course many of them are unique to a given product at the time of manufacture. Some go the route of using power strips that can turn units on and off externally to extend the life of the internal OEM switches.
Joe
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I have 2 original manuals 5A15N Amp and 5B10N Timebase. (so sad I don't have that mainframe anymore!)
Free - but postage to O/S will be about $20A
contact hugh@...
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"I have now seen two 2465 PCB blocks with a burnt-out on/off switch."
"The damage is caused by the arcing across the now-separating terminals, when the machine is switched OFF."
No manual and not right now because I am AGAIN (GRR) downloading a rather large file and don't want to slow it down. Yes I got highspeed internet but it is running through about 100 feet of bookie phone cable.
Enough on that, your problem is not inductive kick. Reason ? Because that unit uses an SMPS. The AC does not go to a coil, it goes to a bridge rectifier, full wave bridge in 240 and half wave doubler in 120. How do I know that ? I had to work on one. In fact I am going to start a thread about exactly why, instead of hijacking yours.
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There is a small tektronix knob on thingiverse, I haven't tried printing it
yet, but plan too as I'm in need of a knob for a 2213...
Getting the color right is always the key, but 3d prints can be painted and
the paint stays on pretty good, also I have a pretty nice beige color of
polycarbonate, I use it to make replacement HP switch covers, looks pretty
good.
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On Tue, Jul 31, 2018 at 7:31 AM, <johnasolecki@...> wrote: Just curious, has anyone ever tried 3D printing replacement knobs? My Tek
equipment is all intact but I could use a few HP knobs as well as a couple
of Genrad. That might be a nice little sideline for someone to help justify
the cost of a good quality printer. Getting the color bang on would be an
issue and a 4th axis to rotate the knob as it's being made might be
necessary for really good authenticity. Still, worth exploring?
--
Keith Refior
keith@...
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3.
How can there be a final verdict when the problem is
not yet defined?
-Chuck Harris
M Yachad wrote:
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So what's the final verdict?
1 or 2?
Mounted across the switch terminals, EITHER
1. A 10nF DC rated capacitor up to about 3000VDC
OR
2. A 10nF AC Class X/Y capacitor rated to about 500VAC
??
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G?ran Krusell
Lyle Bickley
Joseph Strickland
Jeff Urban