Question on which NIM amp for a 3He detector?

This area is for discussions involving any fusion related radiation metrology issues. Neutrons are the key signature of fusion, but other radiations are of interest to the amateur fusioneer as well.
User avatar
Dennis P Brown
Posts: 3160
Joined: Sun May 20, 2012 10:46 am
Real name: Dennis Brown

Question on which NIM amp for a 3He detector?

Post by Dennis P Brown »

I decided to upgrade to a complete NIM system for neutron detection with my 3He tube. I ordered a NIM box, a HV power supply (0-5 kV) and a rate counter but have no idea which course amplifier is a better 'fit' (I have a self powered pre-amp already.) Which of these make the most sense for a system? A few words on how they differ would be useful, too:

TENNELEC TC 246 AMP/SCA COARSE GAIN MODULE
or
TENNELEC TC265A LOW/WIDE AMP/SCA NIM BIN PLUG IN (op & service manual available)

or(maybe not a proper amplifier(?))
Ortec Delay Line Amplifier Nim Bin Module Model 460

All are on Ebay, of course. Appreciate any input
Alex Aitken
Posts: 250
Joined: Mon Dec 08, 2003 5:33 am
Real name:

Re: Question on which NIM amp for a 3He detector?

Post by Alex Aitken »

The TC246 has a spectroscopy (shaping) amplifier, so that ought to work well. A give away for these devices is a knob to change the shaping time. Some of these will go from 100ns to 10us in 5 or so steps. Each setting is a different trade off between voltage noise and current noise. Be aware they often have two sets of numbers, one double the others. This is not extended range, but a different way of measuring the time. A bit like the Peak Music Power Output scam for speakers.

The TC265A does not seem to be a spectroscopy amplifier. Amp/Discriminator.

The ORTEC model 460 is a spectroscopy amplifier, but the method it uses is different. It's manual suggests it's designed for scintillation detectors. Probably best to give this one a miss.

I may be talking rubbish, but I think I've read that Tennelec and Canberra 9pin preamp connectors have different pin outs.

It's difficult to know with these things when you are buying a 50 year old card. I've recently bought some NIMs and am looking at some others but there are a few pitfalls. My mini bin has no access or space at the back which means NIMs with connectors on the back don't fit, and (I think) no 115vac which some cards need. I would look at the TC246 but also consider other models, hopefully other members will have experience.
User avatar
Dennis P Brown
Posts: 3160
Joined: Sun May 20, 2012 10:46 am
Real name: Dennis Brown

Re: Question on which NIM amp for a 3He detector?

Post by Dennis P Brown »

That is certainly helpful and very informative, too. Thanks' Alex.
User avatar
Richard Hull
Moderator
Posts: 14992
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: Question on which NIM amp for a 3He detector?

Post by Richard Hull »

Alex is correct. In an abortive effort to keep the preamps and NIM bin coarse amps "in-house" Tennelec did indeed screw with their 9 pin preamp power plugs. This aced out what was a defacto standard for this plug. I imagine after some one bought their preamp and plugged it into there Ortec Nim amp and perhaps blowing up the Tennelec preamp, they got wise and went back to standard 9 pin power configuration. So.........any use of anything Tennelec that you buy be it a preamp or a bin mount amp, where you will need to use the 9 pin for power you need to tear into it and figure out the wiring for the voltages and ground.

You are in luck.
I have the pinouts and they are as below

Stock Ortec 9 pin industry standard more or less
Note: the +/-6volt buss is just never used much anymore. 95% of all modern bins, while all are buss wired for it, do not ever power it up from the main bin supply. Heavy 2-3 slot +/- switchable nim bin plugins tend to power up this 6 volt buss using the 120vac buss to power this plugin supply to activate the 6 volt buss.

1 ground
2 ground
3 +6v
4 +12v
5 -6v
6 -24v
7 +24v
8 n/c
9 -12v

Tennelec oddball 9 pin (not on all tennelec) However this was their pin-out on their TC203 as noodled out by me... they used only +/-12v
Again, you must open the Tennelec preamp or plug-in amp to be sure. The easy check is to put an ohmmeter on the case or chassis and then probe pins 1 and 2. These should be shorted to ground if it is a standard Ortec compatible.

1 P/Z in
2 n/c
3 +12v
4 Preamp test in
5 Detector bias
6 Ground?
7 n/c
8 -12v
9 ground

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
User avatar
Richard Hull
Moderator
Posts: 14992
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: Question on which NIM amp for a 3He detector?

Post by Richard Hull »

I checked my old win98 computer. I used this in the late 90's when just getting into NIM and found an image of the TC203 that I bought off e-bay and my neophyte write up on it from back then. You definitely needed their preamp. I attach the info. The ancient word file was converted to PDF and the fonts are weird from the original, but very readable.

At the time, this was a really sweet amp. The adroit could easily turn the 9 pin to a compatible.

Richard Hull
Attachments
tc203blr.JPG
TC203BLR.pdf
(131.23 KiB) Downloaded 225 times
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
User avatar
Dennis P Brown
Posts: 3160
Joined: Sun May 20, 2012 10:46 am
Real name: Dennis Brown

Re: Question on which NIM amp for a 3He detector?

Post by Dennis P Brown »

Thanks Richard for the excellent information - needless to say, not exactly available anywhere else.
User avatar
Dennis P Brown
Posts: 3160
Joined: Sun May 20, 2012 10:46 am
Real name: Dennis Brown

Re: Question on which NIM amp for a 3He detector?

Post by Dennis P Brown »

Here is a question on the NIM box and what it does - you provide pin read outs with voltages for the given pins, so if one provides those voltages to the pins in a given NIM application device, then it should power up and operate (if working)? I'm asking because one of the application devices arrived but the NIM box hasn't and isn't likely for a week or more. So, I'd like to test it at some point maybe sooner rather than later and if there are issues, able to return it before the return time lapses.
Alex Aitken
Posts: 250
Joined: Mon Dec 08, 2003 5:33 am
Real name:

Re: Question on which NIM amp for a 3He detector?

Post by Alex Aitken »

Depending on the unit, it could be using +24 +12 +6 -6 -12 -24 ~117 or +200. I understand 200v is rarely supported or used, a lot of pulse testing stuff seems to sync to 117 to reduce noise but probably nothing needed for spectroscopy. You could check the back of your NIM to see what is used, and I've done this a lot just to see what will work. My 35+ has a NIM slot and I think more voltages are supported than in my bin. An 8075 hit my door mat today and it uses all but 1 of the low voltages. I'd wait for the bin to come, and I'd check the lines levels are right and clean before plugging anything in.
User avatar
Richard Hull
Moderator
Posts: 14992
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: Question on which NIM amp for a 3He detector?

Post by Richard Hull »

Both the bins and all modules are easily checked for what voltages are their in the case of the bin. No bin is even needed to determine what any plug in needs to function.

Take one side or the other off of the plug-in NIM module. Look at the power end of the plug internal NIM power connections to see what wires exit the plug and run to the electronics card. Rarely, in some cases, at the base of the faceplate of the module, the power requirements are clearly printed with the voltages needed and the current ratings or "draw" in that supply.

It is automatically assumed that if you own a NIM bin or modules that you have a full diagram of the NIM power plug buss system. without it you are adrift in a sea of calamity.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
User avatar
Richard Hull
Moderator
Posts: 14992
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: Question on which NIM amp for a 3He detector?

Post by Richard Hull »

Both the bins and all modules are easily checked for what voltages are their in the case of the bin. No bin is even needed to determine what any plug in needs to function.

Take one side or the other off of the plug-in NIM module. Look at the power end of the plug internal NIM power connections to see what wires exit the plug and run to the electronics card. Rarely, in some cases, at the base of the faceplate of the module, the power requirements are clearly printed with the voltages needed and the current ratings or "draw" in that supply. (photo supplied below)

It is automatically assumed that if you own a NIM bin or modules that you have a full diagram of the NIM power plug buss system. Without it you are adrift in a sea of calamity. (diagram below)

Often modules that are whole within themselves will only have a few gold pins in their NIM connector.
Look there into its plug to see what power is really needed, using the supplied pin-out diagram.

Richard Hull
Attachments
Notice the top of the plug is for DC power and the bottom of the plug is for 120volt AC buss power to modules using a power trnasformer internal to the module.
Notice the top of the plug is for DC power and the bottom of the plug is for 120volt AC buss power to modules using a power trnasformer internal to the module.
Carefully enlarge this image by clicking on it and read all the power requirements fully printed in the lower right corner along with current draws.  AC means there is a power transformer in it that uses the NIM AC power buss.  It still used buss power of +12 and -12 volts as well. the Ortec log/lin to the left also has its power needs printed out on it.
Carefully enlarge this image by clicking on it and read all the power requirements fully printed in the lower right corner along with current draws. AC means there is a power transformer in it that uses the NIM AC power buss. It still used buss power of +12 and -12 volts as well. the Ortec log/lin to the left also has its power needs printed out on it.
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
User avatar
Dennis P Brown
Posts: 3160
Joined: Sun May 20, 2012 10:46 am
Real name: Dennis Brown

Re: Question on which NIM amp for a 3He detector?

Post by Dennis P Brown »

Thank you Richard and Alex. Being new and certainly never having really seen a NIM in any detail, this is all rather strange. I understand the need for a NIM HV module (and assorted cables - ugh; too many types, now I need to order another), a NIM case to hold/power these modules, a pre -amp (for the 3He tube; and thank you Richard for locating that on Amazon), a NIM based Amplifier, and a scalable counter. However, Richard's Timer/multi-scaler in his NIM box is unknown to me. Exactly what is that and what is its purpose in a detector system?
User avatar
Richard Hull
Moderator
Posts: 14992
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: Question on which NIM amp for a 3He detector?

Post by Richard Hull »

Remember the NIM system is a nuclear physics electronic Erector set. Kids with this NIM Erector set (Mechano for the euros), are expected to make anything the mind might imagine, nuclear instrument wise. If you detect something like a pulse that is recurring via pre-amplification, discriminating, shaping, amplifying, it just might be nice to be able to count say a million or more of these pulses a minute or 149 pulses over 24 hours.

This is the use for this module. To receive pulses, count and display them over any user selectable time period. In the case presented in the preceding image, a fist sized piece of U ore was placed under a 2" pancake GM tube powered to a set voltage of 900 volts using a NIM bias set module. The signal for each pulse from the tube is fed to a NIM coarse amplifier module where it is amplified and clipped to a fixed voltage. It is then massaged to a specific shape with another NIM module. This nice clean signal is then sent to an analog ratemeter module with a meter and then onto a digital ratemeter/Timer NIM module set to count for one minute and stop. This has been done and the piece registers an inaccurate emission rate from the exposed surface of the U ore rock of over 226,000 particle detections 1 cm distant from the pancake probe over a 60 sec time period.

Inaccurate, I say, as the pancake will detect only surface alphas to about 70%, Near surface betas to 85%, and gammas from varying depths to under 5%. In addition there are pulses lost or not counted over that one minute count time due to "pile-up", not accounted for. My hand that placed the rock under the pancake suffered a far greater maelstrom of particles than this per unit time from this bland and un-impressive rock.

Thus, the industry making NIM modules has long ago figured out just the right modules to make my custom GM counter in their erector set toy nuclear building block structures. It was up to me to put them in order and tune them up. The counter/timer/rate meter module was my optical readout amid a mass of electronic signals originating in the pancake GM detector.

This same NIM toy module could have been used by the adroit hand armed with a myriad of other NIM toy modules to count neutrons from a BF3 tube, an 3He tube or a PMT with proper scintillator.

With the introduction of a simple single channel analyzer NIM module placed in my GM chain above, had I used the sodium iodide PMT detector instead of the above GM pancake, I could have easily counted only the 610 KEV gamma emission from the rock's contained Bismuth 214, radium daughter.

I have many NIM bins and many modules. I supply a simple early image of this one specific system setup looking at a very weak U ore sample.

Nice to have a bunch of NIM toy modules if you are doing nuclear measurements.


Richard Hull
Attachments
Early 2005 NIM setup to catagorize my specimens from a U hunt in Utah of that year.
Early 2005 NIM setup to catagorize my specimens from a U hunt in Utah of that year.
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
Rex Allers
Posts: 570
Joined: Sun Dec 30, 2012 3:39 am
Real name:
Location: San Jose CA

Re: Question on which NIM amp for a 3He detector?

Post by Rex Allers »

I don't have any NIM stuff here, myself, but I found Richard's post of the NIM connector pin-outs a good reference to save. But it prompted me to look a bit more.

Looked for the image source and found it in:
https://www.osti.gov/servlets/purl/7120327
(page 25)

This is a scan of a NIM Standard document from 1990

Richard's shared image is a bit truncated at the bottom.
Both versions suffer from some noise (dark speckles) in the scan of the original paper document.

I extracted a new image from that 1990 document and spent some effort cleaning away most of the visual speckles. So I made a PNG version that is a little more complete of the original and hopefully a little easier to read with the clean-up.

'NIM Conns 1990.png'
NIM Conns 1990.png

Then I searched hoping to find a similar document that was already cleaned up.

I found one in document from a German company here:
https://www.fastcomtec.com/ftp/manuals/nim7022-7033.pdf

(called Page 12 but actually page 7 of the 8-page PDF)

I have extraced it as:
NIM Conns 2.png
NIM Conns 2.png


This one was clean without any image editing. It also has a few more pin functions defined than were in the original from 1990.

Since most modules only use a small subset of the connector pins, it is unlikely that we amateurs will find newer modules that use these additional pin definitions. But I thought it was good to see this newer connector specification page.

------
So as I said, I have no direct experience with NIM stuff. Does this look good and helpful?
Should I post it again in the NIM FAQ Richard started and recently bumped up with an edit?
Rex Allers
User avatar
Dennis P Brown
Posts: 3160
Joined: Sun May 20, 2012 10:46 am
Real name: Dennis Brown

Re: Question on which NIM amp for a 3He detector?

Post by Dennis P Brown »

Thanks Alex for this further work, I've made print outs. These are extremely useful to both ID pins but aslo if one needs to setup a module w/o a NIM box
Alex Aitken
Posts: 250
Joined: Mon Dec 08, 2003 5:33 am
Real name:

Re: Question on which NIM amp for a 3He detector?

Post by Alex Aitken »

It's Rex, not me! :)

Thanks Richard and Rex for the info. Due to lack of experience with NIMs I took a back seat. My Canberra card has no power markings but my Tennelecs do and this seems the norm for other big brands. I've probably stared at the connector in a dozen ebay listings and completely missed the writing on the front. *red face*.

I had cause to take the back off my bin, and most of the power lines come from what looks like a 1980's switch mode supply. Something of a nightmare. The -24v line is provided by it's own transformer board with a linear regulator and a big cap. There is no AC or high voltage at all into the back-plane. The 6v and -6v lines are 5v and -5v deliberately. Makes me wonder if that is going to be a problem. I'm wondering if it is possible to get the metal pins for the connector housing and retrofit AC from a step down transformer. I'm also wondering if cards that expect to draw 6v, say to generate 5v logic internally will fail to work. I looked at the power supply wondering if I could tweak the voltage, and though it is producing 5 voltages it has a bank of only 4 linear pots.
User avatar
Dennis P Brown
Posts: 3160
Joined: Sun May 20, 2012 10:46 am
Real name: Dennis Brown

Re: Question on which NIM amp for a 3He detector?

Post by Dennis P Brown »

Oops, well, thanks to both Rex and Richard. These posts are great and really are giving me insight about NIM's (I didn't know what that that acronym even stood for ... .) I very much want to look at the insides of the NIM main box when it arrives and get a feel for its mode of operation. Certainly I do need to test the NIM modules I purchased and only a few days ago realized I didn't have all the required/correct HV cables for the PS module to connect to the pre-amp (I do have the correct ones for the 3He detector to the pre-amp) - the various flavors of those cables one could write a number of posts on. All part of the NIM experience, I guess.

I printed those NIM posts maps out and will mount them in my lab room. Those posts should get their own FAQ entry.

I am finally upgrading the pre-amp to 3kV caps as Richard suggested. I am considering a full wav single stage voltage multiplier for the transformer but that, if I ever move it forward, will get its own post. Diodes are my limiting factor.
User avatar
Richard Hull
Moderator
Posts: 14992
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: Question on which NIM amp for a 3He detector?

Post by Richard Hull »

I went back to my NIM FAQ of 2001 and added the pinout page above to the FAQ. So it is OK as originally written with the new included diagram pinout.
For those old and new alike who would know NIM check out the updated FAQ located at...

viewtopic.php?t=5107

You will find a lot in this FAQ in the form of multiple responses that add to it.



Regarding 6v lines....Forget they exist! In my new homebrew NIM supply work posted recently at.....

viewtopic.php?t=14544

I am currently planning on putting +/- 5volts on those buss lines. (brings NIM into the TTL and 5 volt electronics world of the 1970-2000 range of electronics for homemade NIM modules.) For some strange reason NIM modules using only discrete components were manufactured into the 1990's!!!
In many cases, I realize, OP amps that could replace 10 transistors were not all that fast compared to well designed discrete electronics. Add to this, the signal levels were originally designed when none of this IC stuff was around. Manufacturers were forced to live up to the old standards if they wished to remain module compatible across other manufacturers modules.

My supply, as I note, will be to design my own modules with all modern circuitry in them. +/- 5 volts is a must. Placing a simple power diode or two in series with a normal bin's +6 volt line, within my homemade module would make my 5volt TTL work fine. Another option is that my module could use the +12 volt NIM buss line to feed a linear 5 volt regulator within my module. Although it would be a waste of 12 volt power in the 5 volt regulator under nominally heavy +5 volt demands.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
User avatar
Finn Hammer
Posts: 298
Joined: Sat Mar 05, 2016 7:21 am
Real name: Finn Hammer
Contact:

Re: Question on which NIM amp for a 3He detector?

Post by Finn Hammer »

Richard,

If voltage drop related losses in your linear regulator is your worry, try this little component:


https://www.mouser.dk/ProductDetail/REC ... 5HVA%3D%3D


It is a switcher, with neglectible losses.

Cheers, Finn Hammer
User avatar
Richard Hull
Moderator
Posts: 14992
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: Question on which NIM amp for a 3He detector?

Post by Richard Hull »

Actually I own 5 of those tiny little buck regulators from Marlin P Jones and 5 similar boost regulators. I will try one of them. However, they are all positive boost and buck. and the NIM ground buss might not like flipping them for negative regulation. Always flys in the ointment.

https://www.mpja.com/Adjustable-15-37V- ... /30149+PS/

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
User avatar
Dennis P Brown
Posts: 3160
Joined: Sun May 20, 2012 10:46 am
Real name: Dennis Brown

Re: Question on which NIM amp for a 3He detector?

Post by Dennis P Brown »

Since the NIM box came in, and is one of the reasons I started this thread, I have a few questions.

The NIM box appears to work fairly well (it was sold as non-functional since the power cord was cut off. See pic.) The unit provides +/-24 and +/-12 volts but the +/- 6 volts doesn't seem to be working. May or may not be important for other modules.

I installed the HV output module (unit on far left; bought separately) and that works - I used both a HV probe and a multimeter to read its output. It covers 5 KV range (neg.)

So I assume it has an internal switch for positive since the unit has lights for neg./pos. polarity - in any case, I assume the negative is what detectors use?

Also, the NIM box has a digital (ancient red diode array display) display module that measures either Hz or kHz (has a switch). On the back is a micro-coaxial connector. Again, not clear on what that unit is useful for? Guess I can hook up a signal to it and see if it reads kHz/Hz. But why would one care enough to build such a one-trick pony?

Finally, a "Delay generator" was included in something else I bought - what use is a delay generator? That is, is it of any use for neutron or x-ray detection? Kinda curious.

Meanwhile, I will be waiting for the amp and counter modules. Also, another HV coaxial cable in order to enable hooking up my pre-amp to the 3He detector. Only then can I try real testing to see what is involved with trying to operate these rather complex but interesting units.

As an aside, check the vacuum in my fusor chamber - reading 7.5 torr after two months with no pumping. For those that wonder about the issue of a slow leak compared to out gassing - this is a good example of the later. My chamber rises a few microns a minute when the pump is closed off but that rate slows rapidly. That is a sign of out gassing. A leak would continue and raise the pressure back to atmosphere (or close to it in a rather quick manner.
Attachments
20220707_144155.jpg
20220707_144148.jpg
Last edited by Dennis P Brown on Thu Jul 07, 2022 4:12 pm, edited 1 time in total.
User avatar
Liam David
Posts: 518
Joined: Sat Jan 25, 2014 5:30 pm
Real name: Liam David
Location: PPPL

Re: Question on which NIM amp for a 3He detector?

Post by Liam David »

One of the three switching power supply modules is likely busted. It could be dead electrolytics as that's what temporarily killed my crate. Crates usually get a little toasty while running and even high-temp-rated caps often don't survive 40 years like that. It could also be the (SCRs?) or bridge rectifiers on the back heatsink if someone plugged HV into the wrong port.

Most detectors take positive HV. Yours was likely hooked up to an HPGe detector, which typically uses around -4500V. There should be an internal switch or swappable jumper that's listed in the manual. the Nuclear Physics Lab website by Tim Koeth et. al. has a bunch of NIM manuals assembled.

You won't have any use for a delay line unless you're doing coincidence or other time-sensitive stuff.
User avatar
Dennis P Brown
Posts: 3160
Joined: Sun May 20, 2012 10:46 am
Real name: Dennis Brown

Re: Question on which NIM amp for a 3He detector?

Post by Dennis P Brown »

Thanks, Liam. Got a feeling that the jumper is well marked. I should check it tonight. Didn't know which polarity detectors tended to use. Used many detectors over the years but all were black boxes and have never considered that question till now. Again, thank you.

Electrolytic caps do tend to leak and fail with age; that is an easy check. Pulled the schematics off the web so guess I'll do the diagnostics if any of my not yet delivered units require +/- 6 volts. Likely one will ... ;)

Richard's voltage supply seems far easier to install then any difficult tracing; if the issue isn't obvious, think I'll just order those.

Update: checked the module and yes it had a very simple jumper/bus 'bar' assembly (a mini-circuit board) that just had to be moved to engage the HV positive. See photo's. To say well marked is an understatement; even had instructions and arrows printed on it. They certainly understand scientist ;)
Attachments
Complete circuit board (Reset)
Complete circuit board (Reset)
Close up of "Bus Bar" (reset)
Close up of "Bus Bar" (reset)
User avatar
Richard Hull
Moderator
Posts: 14992
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: Question on which NIM amp for a 3He detector?

Post by Richard Hull »

Note: 95 % of all NIM bins that show a +/- 6 volt test points DO NOT have +/- 6v capability built into their power supplies. I have harped on this for years! Plus and minus 6 volts is as dead as a doornail. Intrinsically a dead duck. 100% of all bins are bus wired for it though. If you want or really need + or - 6v you will have to buy or manufacture a 6 volt plug in module to power the buss. That ancient 6 volt buss was so dead that many manufacturers made it a special order supply item. They did start to manufacture nice plug in 6 volt high current plugin modules to power the bus. As it is hyper rare to find a module ever manufactured to use both the plus and minus 6 volt lines, The 6 volt plug in modules have a polarity flipper board if you have a module that demands only one of the 6 volt buss lines. I own a couple of these heavy two slot 6 volt modules.

90% of all HV bias supplies have an internal polarity flipper board in them. Most are set for positive from the factory. Again, all of this is noted in the original FAQ


I really hate to have to continually write all of this 6 volt and HV polarity flipper board data over and over again.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
User avatar
Dennis P Brown
Posts: 3160
Joined: Sun May 20, 2012 10:46 am
Real name: Dennis Brown

Re: Question on which NIM amp for a 3He detector?

Post by Dennis P Brown »

Getting the unit I first down loaded a schematic of the 402A unit's power supply and of course, it shows +/-6 volts in the schematic; however, if I had looked the unit over carefully, I would have seen a placard on the unit stated clearly stating it supplied +/- 12 and 24 volts. You'd think I'd read the FAQ's first ... but no.

Well, it is fun learning about these fascinating units and now having read the FAQ's I have a bit better understanding.
User avatar
Richard Hull
Moderator
Posts: 14992
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: Question on which NIM amp for a 3He detector?

Post by Richard Hull »

If one obtains a powered NIM bin in which the +/-6 volts are supplied within the supply, one may consider oneself most blessed among men. Whoever originally ordered it paid the long buck for that option to power a dead, early standard.

I have only one single module that gobbles up 4 slots and demands NIM +6 v along with +12 volts and the AC mains. It is an ancient Victoreen/Tullamore counter/scaler with preset. It uses six rows of lamps requiring the user to read the final count in BCD. The back panel has a slew of BNC plugs for gates, inputs and outputs, remote operations plug, etc. Inside this piece of cutting edge 60's technology are 6 large, full size electronic PC boards with hundreds of transistors festooned in row after row to obtain the number of J-flipflops and individual diode logic gates and buffering to light the 30 incandescent lamps in a BCD sequence counter. The preset switches have 60 wires scattered like spider webs going to the boards with associated halt gated diode logic matrix. What a piece of individual, hard wired art, miniaturized into a rectangular solid using the new fangled 60's printed circuit technology!

Yes! it works perfectly. I won't sell it, or use it. Its value is in passing it around for a "show and tell" over a crackling campfire while regaling tales of yore as beer and hot dogs are consumed, to the amazement of all assembled.

Ah...Th' good ole daze....

Richard Hull
Attachments
Counter Victoreen close.jpg
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
Post Reply

Return to “Neutrons, Radiation, and Detection (& FAQs)”