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Re: Further to my query of a flashing LED circuit not working

 

On Tue, Nov 12, 2024 at 09:07 PM, Ian Bell wrote:
Can I use an electrolytic 63V, 1uF or another type such as a Tantalum or a 100v Non-polarised type.?
I would think so - yes,? yes, and yes.
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FYI, a Tantalum capacitor is an electrolytic.? The two main kinds of electrolytic caps are Aluminum and Tantalum.
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Electrolytics may not be the world's greatest capacitor type, but should be fine in this circuit.? But be aware that most electrolytic caps have rather wide tolerances on the capacitance value, so the flash rate might differ from ideal by a little.
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The 270 K value for R3 seems awfully large.? But that value depends on the LED and the battery voltage.
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Andy
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Re: any kicad 8 experts here?.

 

Paul?
I agree that it is not the best, but found it quite easy by rotating the parts to approximate the schematic then just link them using the rats nest lines l linked them all up.
Tony
File /Flashing LED circuit_2_PCB layout.jpg uploaded #file-notice

Group Notification
 

The following items have been added to the Files area of the [email protected] group.

By: Ian Bell <genealogyinfo@...>

Description:
Further to my query of a flashing LED circuit not working. (PCB solder side layout)
Re: Further to my query of a flashing LED circuit not working

 

I am also attaching to the files, a scan of the PCB solder side. Hope it is clear enough. The capacitor is located between the resistors R1 & R3.
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Ian
File Notifications #file-notice

Group Notification
 

Ian Bell <genealogyinfo@...> added folder /Further to my query of a flashing LED circuit not working

Description:
Circuit for "Further to my query of a flashing LED circuit not working"

The following items have been added to the Files area of the [email protected] group.

By: Ian Bell <genealogyinfo@...>

Description:
Further to my query of a flashing LED circuit not working
Further to my query of a flashing LED circuit not working

 

Hi there, again,
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Further to my query of a flashing LED circuit not working. From all the comments I've had, it seems as though it is a "dud" circuit, consequently I have gone to the "Plan B" circuit which I discovered when I was searching for a simple flashing circuit. This uses an NE555 timer IC. I will attach the circuit shortly in the files section. To summarise it has the 555 timer, 3 resistors - 100K ohms, 270K ohms, & 470K ohms, 1 capacitor - 1uF, and of course the Red 5mm LED. The circuit uses a 5-12VDC supply. Can I use an electrolytic 63V, 1uF or another type such as a Tantalum or a 100v Non-polarised type.?
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FWIW, I'm putting a navigation type flashing light on top of a building I'm making for my model RR layout.
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Thanks,
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Ian
Re: Chasing the "mythical" NE-1 neon bulb

 

On Tue, Nov 12, 2024 at 02:30 PM, wn4isx wrote:
I'm assuming both 55V-55V were isolated from ground.
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If they were, I think there would be no point to calling it 55V-55V, or 55 volts on each line.? The implication is that each line's voltage is measured against some other reference - presumably, ground.
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But I could be wrong.
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Andy
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Re: current limited npn not allowing NPN to open

 

By the way, the 1K resistor R1 does nothing useful.? Because you drove the Base with a current source, the resistor R1 does not change that in any way.
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Andy
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Re: current limited npn not allowing NPN to open

 

On Tue, Nov 12, 2024 at 04:04 PM, john23 wrote:
Why in saturation Ic/Ib is ver very small?
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Because you can't get any more current than that.? When it is in saturation, it can't turn on any harder and that is all the collector current that is possible.? It is basically limited by the rest of the circuit around the transistor.
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In your case, you subjected the NPN to a base current from 1 mA to 20 mA.? If the transistor's Beta was 200, then the collector current would have to be between 200 mA and 4 Amps.? It is physically impossible.? The absolute maximum collector current in your circuit would be 5/(1K+100) = 4.5 mA, which is MUCH smaller than either 200 mA or 4000 mA.
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In order to get Ic = 4000 mA, the collector voltage would have to be pulled down to -395 volts!? But there is no negative supply voltage in your circuit, so that is just plain impossible.? Transistors can not generate voltages from nothing.
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Andy
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Re: files

 

Hi all,is it possible to attatch a file here?
I just checked the settings, and it says attached files are automatically Stripped (removed from messages) by the servers.? So, don't try.
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... and need to upload the schematic+ board files but cant see how i can do that, Is it possible?
The best way to do that is by uploading them to Files.? It is one of the choices in the menu (on the left if using a PC).? Navigate to Files, then look for the "New/Upload" button near the top.
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Andy
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Re: any kicad 8 experts here?.

 

¿ªÔÆÌåÓý

You can use FreeRoute with KiCad.?



On Nov 12, 2024, at 4:44?PM, Paul M3VUV via groups.io <nanovnauser@...> wrote:

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i gave up on kicad as it has no autorouter,i am trying eagle instead now.

Re: Chasing the "mythical" NE-1 neon bulb was something wrong

 

I recall my mother complaining that she felt a "tingle" when touching the stainless steel edge on her Formica counter top while opening the refrigerator. I was probably 10 at the time but I knew enough to run a ground from the BX cable to the counter edge. It was probably some leakage in the fridge compressor but it took a while for her to convince my father there was something wrong. This was in the early 50's so there were no polarized plugs.

Dan Kahn
On Tuesday, November 12, 2024 at 12:07:25 PM EST, wn4isx via groups.io <wn4isx@...> wrote:


I guess it's time to bring up "The All American Five" and AC/DC operation.
Parts of Detroit were 110V DC up until sometime in the 1960s. An aunt lived there and told me of the woes of getting a TV that worked.
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AC/DC radios most often had one side of the AC mains wired to the chassis. Which gave you a 50/50 chance of a hot chassis given non-polarized 2 conductor power plugs. Later units "isolated" the chassis with a capacitor, still deadly.
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The outer case and knobs were designed to prevent contact with the chassis.
My younger sister pulled Mom's radio off the table, shattered the case. I was told the throw the radio away, saved it, plugged in and it worked. I was 7 and touched the case. Our garage had a dirt floor and I was barefooted and got the urine knocked out of me. My father demonstrated the danger with a light bulb. That lesson stayed with me.
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So if you are restoring an All American Five (no idea why anyone would the performance was amazingly mediocre) be aware the chassis might be hot.
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Oh, the insulation in pre ?1970 Singer sewing machines was marginal and the case could easily be hot.
My older sister was shocked on Mom's Singer.
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And, lights are supposed the have the shell wired to neutral. Even with polarized 2 conductor mains connectors, do not trust the wiring!!!! Been bit once really good because I assumed "surely they wired it
properly at the factory." Nope. shell was hot, switch was in the neutral.
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Trust but verify applies to electronics as well as international weapons treaties.
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Re: any kicad 8 experts here?.

 

i gave up on kicad as it has no autorouter,i am trying eagle instead now.

files

 

Hi all,is it possible to attatch a file here?,i am struggling trying to make a pcb for toner transfer using eagle and need to upload the schematic+ board files but cant see how i can do that, Is it possible?.thanks all.

Re: current limited npn not allowing NPN to open

 

I think you meant Collector-Emitter saturation voltage is around 0.2V, correct?? The Base-Emitter voltage is typically 0.6V.

Re: current limited npn not allowing NPN to open

 

Hello,the purpose of biasing NPN threw current source is to calculate the limiting resistor needed for supplying the base of the NPN.
Why in saturation Ic/Ib is ver very small?
Thanks.

Re: Chasing the "mythical" NE-1 neon bulb

 

On board the USS John F Kennedy CV 67 the 110 volts was 55 volts on each line. There was no neutral. Any higher voltage was hard wired to ships power.

Re: Chasing the "mythical" NE-1 neon bulb

 
Edited

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:
Yes using the AC mains will work nicely, but requires extreme caution that new comers to the hobby might not fully understand. ...
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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Look up death capacitor
Scroll down to line #7? "The Infamous Death Capacitor???!!! Very Important !!!"
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.
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The meds sneaked up on me.
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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.
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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.
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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:
Three phase has three legs 360/3 = 180 degrees apart.
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Re: "Three phase has three legs 360/3 = 180 degrees apart."
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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.?
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And, wow, you are able to multiply 12V to 20K!
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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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