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Re: 3D Printing / Milling Tektronix parts
So far as I know, I don't need any. The post was mostly for Tam's benefit. I'm a severe technogeek who has been obsessed with all the things there are to be done and all ways there are to do them since childhood. And have a 5000 volume technical library to help me remember the things I forget.
A lot of people tend to assume that injection molding plastic takes huge expensive machines. While that is true of high volume production, at low volumes it becomes much simpler and building a machine and molds is a hobby shop level project. |
Re: 464-466 w/dm44
Hi Jim,
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Feel free to send me the pictures (PM to fabio.tr3visan@...). I will be glad to post it to the photos area of Tekscopes.io, and reply to you with a link to the folder. Rgrds, Fabio On Fri, Aug 3, 2018 at 03:07 PM, Jim Olson wrote:
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Re: Snubber capacitors
As did working with a 10 Henry choke back 25+ years ago for me.? Transistors kept dying when I switched off the power, and when I had my finger on the wrong spot, I instantly knew why!? Zap, a lesson I will never forget!
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Jim Sent from my Verizon, Samsung Galaxy smartphone -------- Original message --------From: Chuck Harris <cfharris@...> Date: 8/3/18 6:09 AM (GMT-08:00) To: [email protected] Subject: Re: [TekScopes] Snubber capacitors
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. |
Re: 464-466 w/dm44
Hakan, this 464 is sn#B145646 it has the latest dash number -16 A6 inter board and the 3324-01 board is correct. I took some pictures of it but I am not using a photo posting svc. at this time so can i send them to you for your perusual and post it you feel so.
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Jim On August 3, 2018 at 11:10 AM zenith5106 <hahi@...> wrote: |
Re: 464-466 w/dm44
On Fri, Aug 3, 2018 at 04:26 PM, Fabio Trevisan wrote:
The IC controlled Trigger board as well as other improvements was introduced at SN B200000. The Service manuals 464 / 070-4795-00 and 466 / 070-4796-00 are for B020000 and up. Before that SN the Trigger board could be 670-3324-00 through -03. If I interprete the RPR (Replaceable Parts Record) correctly, and it could be wrong, only -02 or -03 would work with DM44. Although no SN limits are given in the RPR there are in DM44 instruction sheet so it is probably right. /H?kan |
Re: 464-466 w/dm44
Fabio I have the pictures but I'm not using any kind of photo posting service it's gotten to complicated and I don't post much to forums anyway so can I send them to you and you can post them up?
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Jim On August 3, 2018 at 7:26 AM Fabio Trevisan <fabio.tr3visan@...> wrote: |
Re: 3D Printing / Milling Tektronix parts
Reginald,
I can make some knobs in castable resin with my SLA printer if someone wants to make some molds. Mike kd5rjz On Thu, Aug 2, 2018 at 6:50 PM, Reginald Beardsley via Groups.Io < pulaskite@...> wrote: I think it worth pointing out that injection molding knobs would not be |
Re: 464-466 w/dm44
Hello Jim,
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I owed and restored a 464 with DM44 (now given to a friend) and I don't think there are any other "optional" boards linked to the presence (or absence) of the DM44. The only optional boards that apply to the 464 / 466 are: A. The optional DC inverter board (option 7)... That one can't co-exist with the DM44 (the inverter uses the same windings on the main transformer that are used to power the DM44). B. The composite video Sync Separator (Option 5), which bears some relation to the A5 sync board and could explain some changes. I did hear once, from someone of this group, there was two versions of the A5 Sync board... one that used the Tunnel Diodes, and another one which used a Custom Tek IC to discriminate the trigger edge. I`m not sure, but maybe this is what the -01 means... I've never landed my eyes, however, on a schematic of the latter, or a later manual that included both. But regardless of this board versioning, It seems rather odd to me that the connections to the J6 are disconnected, and more so, that there is no connection between the top and bottom side THROGUHOUT the board... Moreover, there's nothing about the DM44 vs power to the A5 Trigger board... The DM44 takes its power from its own power supply and it's neither fed by the A5 board, nor the A5 board feeds it. Yet, the only reason I can think of for the through hole plating is missing throughout the board is, either a mass murderer technician stripped them off by careless unsoldering, or yet, that it's a prototype board... If it's the latter case, it could explain many things... Maybe you can take a picture, post somewhere and link it here. KRgrds, Fabio On Thu, Aug 2, 2018 at 11:40 PM, Jim Olson wrote:
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Re: Stan's Scope site
walter shawlee
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) |
Re: Snubber capacitors
Having a resistor R in series with the back emf diode means:
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? - 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. On 03/08/18 14:09, Chuck Harris wrote:
I did a little study on back emf diodes for relays back when I |
Re: Snubber capacitors
Chuck Harris
I did a little study on back emf diodes for relays back when I
toggle quoted message
Show quoted text
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. |
Re: Stan's Scope site
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 -- 73 NM6Y Bickley Consulting West Inc. "Black holes are where God is dividing by zero" |
464-466 w/dm44
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 |
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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