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Re: Chasing the "mythical" NE-1 neon bulb
I have gotten behind on these replies, so I apologize if I am out of sync with things others wrote here.
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On Sat, Nov 9, 2024 at 07:20 PM, wn4isx wrote:
Indeed.? If I remember correctly, the usual current-limiting resistor for a NE-2 type bulb was something like 470 K.? In the USA, 470 Kohms would limit it to 255 uA RMS - which is enough to sting, but I think low enough to (usually) not kill even if it goes through the torso.? I felt that "bite" once when handling a mains-powered circuit with several NE-2 bulbs and the big resistors in the power leads.? It didn't occur to me that the current through such a big resistor was enough to do that.? Duh!
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Remember, it's the current that kills, not the voltage.? Several people have been killed from "only" 9 or 12 Volt batteries, if either the skin is wet enough to reduce the skin resistance, or if the path bypasses the skin.? Beware.
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I have seen that, but it was worse.? Back in the 1960s or so, it was not uncommon to build electronics with two capacitors, one from each AC mains wire to chassis, with 2-prong AC power cords (because 3-prong outlets were not common yet).? The two caps bypassed RF junk.? Now, if your chassis otherwise floats with no connection to earth, then of course that arrangement puts the whole chassis at 1/2 the mains voltage, or around 60 V RMS!? It is current-limited, but maybe not safe.
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Normally that piece of equipment would be wired up to other cables that provided a real path to system ground.? But this thing was considered "portable" (luggable) gear and it could be lugged to another location and used without all those cables.? And then it became bad.? If you had something else nearby that was grounded, and an easy way to touch both at the same time, watch out!
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Even if it was not a hazard to humans, it was sufficient to generate some rather nasty sparks!? (I have to guess that loop inductance played a part in that, too.)
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You might say the current is "only" half of what it would be if there was only one "death capacitor".? But by orders-of-magnitude, there's little difference between X amps and X/2 amps.? Still enough to kill - or do some serious damage.
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This part has nothing to do with neon NE-1 or NE-2 bulbs.? But in the end it is the same idea - watch out for those "small" currents that might not be as small as you thought.
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Andy
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Re: Chasing the "mythical" NE-1 neon bulb
I had a total left knee replaced about 5 years ago. No problem. My right is starting to give me some issues but two months ago I got a shot and I've been good since. I'll have to see how many shots I can take before a replacement is in order. At 84 I think that is OK. Dan Kahn On Monday, November 11, 2024 at 06:48:34 PM EST, wn4isx via groups.io <wn4isx@...> wrote: Em....you try to think after taking 10mg of oxycodone, when you don't handle opiates all that well. I have this insane exercise, lay on my belly with my legs mid thy hanging over the end of the bed, then place 20 pounds on my ankles. All this to straighten my left leg. I had total right knee replacement? in early June and was walking on the leg the next day without a walker, the leg straightened out fully with full flexion (retraction like you are kneeling) within a month, had total left knee replacement and things are going nearly as well, I'm 11 weeks out from my left knee replacement and I'm 8 degrees from full straighten and about the same for flexion. ? The meds sneaked up on me. ? The 20 pounds was "sold" to me as "The easy way to obtain full extension." The physical therapist and I are going to have a conversation on exactly what easy means. ? Yes I should have caught it, or probably not tried posting while the meds kicked in. I didn't think this new formulation would hit so quick, the previous took over an hour, this one takes about 10 minutes. ? Yes it was a foolish mistake and I'm sorry and I will try to avoid such foolish mistakes in the future. ? ? |
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Re: Chasing the "mythical" NE-1 neon bulb
What kind of division do you make 360/3=180 duhh. 360/3=120. On Monday, November 11, 2024 at 04:29:54 PM EST, wn4isx via groups.io <wn4isx@...> wrote: On Mon, Nov 11, 2024 at 09:38 AM, Dan Kahn wrote: Re: "Three phase has three legs 360/3 = 180 degrees apart." ? Once again I demonstrate why one should not post under the influence of opiates for total knee replacement and enduring 'do it at home" PT knee straightening exercises.?
And, wow, you are able to multiply 12V to 20K! ? I wasn't able to multiply 12V with a? Crockroft-Waltpon multiplier to ~600V for a Geiger counter tube. I ended up using a 555>8:1000 ohm with 5 or 6? stage of CW multiplication.? |
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Re: current limited npn not allowing NPN to open
With 1K in the emitter, the most Ic you will see with Vcc of 5 volts is 5ma. Take the transistor out and put in shorts and see what currents will be in each path. Do some basic current flow. On Monday, November 11, 2024 at 05:08:27 PM EST, Andy via groups.io <ai.egrps@...> wrote: I wrote:
? Sorry, that should be I1, not U1. ? Andy ? |
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Re: current limited npn not allowing NPN to open
On Mon, Nov 11, 2024 at 01:38 PM, john23 wrote:
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Because your NPN transistor is in saturation.? Saturation must be avoided if you want current gain.
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Plot Vce.? It is less than 30 mV throughout your sweep.? It is saturated.? In fact, the collector voltage is lower than the base voltage and the collector-base junction has become forward-biased.? Under those conditions, your transistor is not an amplifier.? Current goes backwards out of the collector.
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Now repeat the simulation using this sweep command:
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.dc dec I1 1n 100u 10
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Make sure to delete the plot window, then re-run the simulation, to make sure that the X-axis in the plot is logarithmic.
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When the base current from U1 is smaller than about 10 uA, the transistor is not in saturation, and Ic/Ib is reasonable.? Even when I1 is as high as 20 uA, Ic/Ib is almost 200, even though Vce falls to 0.65 V by that point so it is very nearly (not quite) in saturation.? But above 20 uA, the transistor saturates and Ic/Ib takes a nosedive.
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You can plot Ic/Ib directly.? Just edit the label at the top of the plot pane so that it is "Ic(Q1)/Ib(Q1)".
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Andy
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current limited npn not allowing NPN to open
Hello ,I have build NPN which base is being? biased with a current source ,the? problem that My collector current is very low ?no matter the current i put in the base as shown in the photo and simulation.
Why i cant see the Ic/Ib=beta? ratio? Thanks. /g/electronics101/files/john233/npn_circuit.zip |
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Re: Chasing the "mythical" NE-1 neon bulb
After heat cycling I also did Line (12volt) and load regulation. Try that at 20 KV. Measuring HV with Elector Static VM. I had to design and fabricate all the test fixtures and write the test procedures. Building fixtures using glass PCB and a black adhesive. No screws any where! Triple covered silicon wire and huge HV probes for the scope. I am amazed I can still remember this from 65 years ago! Yes I'm 84 year old. Dan K On Monday, November 11, 2024 at 10:29:24 AM EST, wn4isx via groups.io <wn4isx@...> wrote: Color me out of date for most modern cultural references, but who is Mr. Khan? ? I cycled power supplies with the power switch. I tested each power supply I built for: output voltage no load, voltage change from no to full expected load, with +/-20% above/below 120V at no and full load. burn in at full load for at least 10 hours, if practical, a full 24, then repeat initial test. ? ? ? ? |
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Re: Chasing the "mythical" NE-1 neon bulb
At the time I was working for this company, the requirement was for a Heat/Cool cycle in a Temperature chamber for every production supply. I would put I think about 20 supplies in the chamber and start the Heat cycle. The unique part about it was that the supplies generated sufficient heat that during the heat cycle I had to inject CO2 to cool the chamber to the upper heat limit. These had to run for 48 hours under both Heat and Cold. I used more CO@ then Heat during the cycle. Some supplies were added and some removed during the test time due to availability of production quantities. Also if one failed it had to be removed, reworked and put back in the chamber. After temperature cycling then the entire chassis was covered in a silicon material to insulate the PCB. Later on it was determined the small air gap between the silicon and the chassis cover would spark and interrupt the supply output. It took a longtime to determine the cause of the interruption. I just looked and Venus Scientific where I was employed, was bought by Ferranti in 1981 and they closed in 1987. Dan Kahn On Monday, November 11, 2024 at 10:17:40 AM EST, Diego J. Richmond via groups.io <diegojrichmond@...> wrote: Mr Dan Khan : Please, can you describe the procces of cycling the power supplies ? Was it to test them ? Age a sample of the production ? Bake a coating ? Other motive ? Thanks ! El lun., 11 nov. 2024 11:38, Dan Kahn via <dankahn88=[email protected]> escribi¨®:
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Re: Chasing the "mythical" NE-1 neon bulb
Mr Dan Khan : Please, can you describe the procces of cycling the power supplies ? Was it to test them ? Age a sample of the production ? Bake a coating ? Other motive ? Thanks ! El lun., 11 nov. 2024 11:38, Dan Kahn via <dankahn88=[email protected]> escribi¨®:
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Re: Chasing the "mythical" NE-1 neon bulb
Three phase is120 degrees apart! I also worked for a firm making HV (20KV) power supplies for CRT displays. Luckily there was hardly any current available. It was based on a 12 volt square wave oscillator feeding a cap doubler with many chip caps. I had to cycle the supplies through a temperature chamber while still in the open chassis condition. These were all powered ON and only the one to be removed was OFF. Once while removing an OFF supply I touched one of the ON ones. After picking myself up from the floor I changed the process to shut all units under test OFF and restart after the change over. Lesson learned. Dan Kahn On Sunday, November 10, 2024 at 04:03:12 PM EST, wn4isx via groups.io <wn4isx@...> wrote: I've survived contact between 120 hot and ground, pretty sure 220 would have left a steaming cinder. ? I've also survived contact with 60kV (yes 60!) when another tech turned on a GE BW projection TV. Knocked me on my butt. The other tech was fired on the spot. We later found out that model TV produced fairly moderate X-rays. We tested one with a sheet of X-ray film wrapped in black paper. After an hour and 6" ?away, the film was exposed to 50% density. The radiation safety people in main campus had a near melt down and we were ordered to "Permanently disable them." I cut the power cords off and sent them to the radiation safety people. "Not permanent enough." So I removed the power supplies and took a hammer to them and sent the mess of parts to them. "Good job." ? GE refunded the full price and sent people to retrieve the remains. They were somewhat less then thrilled over the missing power supplies. ? We were informed "We have a fix." Radiation safety had red lined the projection TVs and wouldn't back down. ? ? 220 at ?5?A frightens me. You can get 240 in a typical US home [there are homes with 120V service], but you'd have to work at it, either the water heater or clothes drier would be the best place to fry yourself. ? Or the breaker panel (AKA load center to be pedantic.]? ? ? But at least we don't use ring circuits. ? A life time ago, 1988, I was tasked with gathering the gear for a 6 week field TV production in England ( but not Wales or Scotland) and Ireland. A British company that made TV Digital Effects Units saved my bacon by faxing me information on all the electric wiring systems our team was going to run into. And I had to explain to the cost management people why I was on the phone to a England for 4 hours. ? We ended up using 3 1kw 220>120 isolation transformers and somehow the US State Department got the British Home Office and Irish equivalent to issue nationwide waivers allowing us to not connect to the building electrical ground. ? I didn't sleep well until our crew was safely home.?? ? Sir, you can take your 220V, ring circuits, etc,? and keep them. For younger electrical enthusiasts ? And this one is critical! ? Ward Silver's books on grounding are very useful for the US ham and electronics nut, but are totally unsuitable for the British Isles!!!!! ? Note: From the...."overview pdf" Chapter 3 AC Power System Grounding "Fig 3.3 shows a US power pole two phase supply, which is not applicable to GB, where a two phase and neutral supply is not usually provided to domestic premises."? ? Electricians would scream "not two phase, split phase!" because, to them, phase is either single of three . Three phase has three legs 360/3 = 180 degrees apart. ? Once again our common language can bite us in the rump. ? As to be fairies because we use 110 (actually 120)... Next time you come over, you grab 120 hot and 120 neutral and see how you like it. ? |
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Re: Chasing the "mythical" NE-1 neon bulb
I recently saw a video that said construction sites in England us a split phase 110v line that is 55V on each leg.
Giving you 55v to ground if you happen to find yourself in that position. 55V is enough to let you know, but highly unlikely to kill you.
They deem it safer than their 240 System. |
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Re: any kicad 8 experts here?.
¿ªÔÆÌåÓýTry [email protected] they have always been very helpful.
On 10/11/2024 22:06, miktrain via
groups.io wrote:
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Re: Chasing the "mythical" NE-1 neon bulb
¿ªÔÆÌåÓýIn those olden days,? neon bulbs could be used as computer elements.? Flip-Flops in particular.? But the circuits were touchy at best and one of the techniques was the use of radioactivity to make the trigger more reliable in both time and voltage.? The problem with voltage threshold to light up is that cosmic rays will lower the threshold and fire the bulb somewhat randomly.? Higher voltages will strike faster die to electron emission from the electrodes, but then the ability to make things like flip-flops becomes more difficult.? I still have one (I think!) of the small handbooks that showed circuits for oscillators, flip-flops, etc.? So I made some of them some 60+ years ago.? I may recall, perhaps incorrectly, that hydrogen thyratrons also used radioactivity to stabilize their firing potentials.? I experimented with them, too, making a color organ before SCR's were so easy to use.Chas On 11/9/2024 3:56 PM, Andy via
groups.io wrote:
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Re: An very EXPERT on the battery PowerBank for phone?
You have to toggle the USB input data line to the power bank (PB)
this will signal the processor or logic in the PB to increase to full voltage
and full current within its specifications.
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ie When you plug in your device, use the 2-3 volts to run
some logic to send appropriate sequence to the data line into the PB
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There's lots of info all over the net and the published spec as well
on the two data lines which are between power and zero volts on
Eg the USB 1 connector
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All best
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Mike Massen,
Perth, Western Australia |
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Re: Chasing the "mythical" NE-1 neon bulb
On Sat, Nov 9, 2024 at 04:10 PM, wn4isx wrote:
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claims they used a tiny amount of radioactive Krypton, not in the electrodes but in the envelope.
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Andy
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Mike
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