Non Ohmic Constant Voltage Drop "Resistor"

Hi Robert, Yeah hitting it at the right time so that it stops at the right point is the "smart or lucky" part.

George H.

Reply to
George Herold
Loading thread data ...

ranslates into electrical terms. But if you damp a mechanical oscillator w ith friction, such that it's "very hard"*, then you end up stopping the sys tem in a state that still has some potential energy. (Unless you are lucky , or smart.) Where the spring force is not enough to over come the frictio nal force. I'm not sure how that translates to the LC-fristor case. But m aybe it leaves some charge on the cap???

y stored in the system.

pg

You've probably forgotten but it was moi that started the electrical fricti on thread on SED. (Search for "electrical friction".)

My question is what happens if you turn it on hard. (I've got Phil H's nic e LTspice sim stored maybe I can play this weekend.)

George H.

Reply to
George Herold

The best way to remove the energy from a resonant LC is to short it when the inductor current is zero, or open it when the capacitor voltage is zero. Both require accurate timing of the switching action. Slappin a resistor across it can be done at any time, asynchronously, but takes a while to burn off the stored energy.

--
John Larkin         Highland Technology, Inc 

jlarkin att highlandtechnology dott com 
 Click to see the full signature
Reply to
John Larkin

With two switches, you could open the inductor and short the capacitor, and dump all the stored energy instantly.

(Expecting some tedious git to argue about the meaning of "instantly")

--
John Larkin         Highland Technology, Inc 

jlarkin att highlandtechnology dott com 
 Click to see the full signature
Reply to
John Larkin

On Fri, 19 Sep 2014 05:51:45 -0700 (PDT), George Herold wrote:

Try this at higher current:

Version 4 SHEET 1 880 680 WIRE -224 32 -432 32 WIRE -80 32 -224 32 WIRE 208 32 -80 32 WIRE 80 128 32 128 WIRE 208 128 208 32 WIRE 208 128 144 128 WIRE 256 128 208 128 WIRE 368 128 320 128 WIRE -432 160 -432 32 WIRE -224 160 -224 32 WIRE -80 160 -80 32 WIRE 32 192 32 128 WIRE 160 192 32 192 WIRE 368 192 368 128 WIRE 368 192 240 192 WIRE 32 272 32 192 WIRE 80 272 32 272 WIRE 208 272 144 272 WIRE 256 272 208 272 WIRE 368 272 368 192 WIRE 368 272 320 272 WIRE -432 368 -432 240 WIRE -224 368 -224 224 WIRE -224 368 -432 368 WIRE -80 368 -80 240 WIRE -80 368 -224 368 WIRE 208 368 208 272 WIRE 208 368 -80 368 WIRE -80 400 -80 368 FLAG -80 400 0 SYMBOL diode 80 144 R270 WINDOW 0 40 7 VTop 2 WINDOW 3 69 45 VBottom 2 SYMATTR InstName D1 SYMATTR Value Di SYMBOL diode 256 144 R270 WINDOW 0 44 17 VTop 2 WINDOW 3 72 53 VBottom 2 SYMATTR InstName D2 SYMATTR Value Di SYMBOL diode 80 288 R270 WINDOW 0 -33 18 VTop 2 WINDOW 3 -6 58 VBottom 2 SYMATTR InstName D3 SYMATTR Value Di SYMBOL diode 256 288 R270 WINDOW 0 -33 21 VTop 2 WINDOW 3 -6 60 VBottom 2 SYMATTR InstName D4 SYMATTR Value Di SYMBOL current 240 192 R90 WINDOW 0 39 92 VBottom 2 WINDOW 3 11 -13 VTop 2 SYMATTR InstName I1 SYMATTR Value 5m SYMBOL ind -64 256 R180 WINDOW 0 49 82 Left 2 WINDOW 3 47 41 Left 2 SYMATTR InstName L1 SYMATTR Value 1m SYMBOL cap -240 160 R0 WINDOW 0 -54 14 Left 2 WINDOW 3 -57 54 Left 2 SYMATTR InstName C1

SYMBOL current -432 240 R180 WINDOW 0 21 -17 Left 2 WINDOW 3 -174 -162 Left 2 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName I2 SYMATTR Value PULSE(0 1 0 0 0 10u) TEXT 88 400 Left 2 !.model Di D(Vfwd=0) TEXT -216 -32 Left 2 !.tran 10m TEXT 112 -16 Left 2 ;Frictional equivalent resistor TEXT 240 32 Left 2 ;JL July 12, 2013

--
John Larkin         Highland Technology, Inc 

jlarkin att highlandtechnology dott com 
 Click to see the full signature
Reply to
John Larkin

How fast is that, John ?:-] ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
 Click to see the full signature
Reply to
Jim Thompson

As much time as it takes the average git to whine about the meaning of "infinite." 40 milliseconds or so.

--
John Larkin         Highland Technology, Inc 

jlarkin att highlandtechnology dott com 
 Click to see the full signature
Reply to
John Larkin

Chain yank accomplished >:-} ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
 Click to see the full signature
Reply to
Jim Thompson

And gitness confirmed.

--
John Larkin         Highland Technology, Inc 

jlarkin att highlandtechnology dott com 
 Click to see the full signature
Reply to
John Larkin

OK. Make your own Forward/Reverse Recovery Subcircuit. ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
 Click to see the full signature
Reply to
Jim Thompson

Remind me, did I contract with you for that?

I told the customer to jump into the closest, preferably polluted, crocodile-infested, lake, so I don't need a diode recovery model just now.

It wouldn't be hard to do as a pure behavioral thing. I've done that to simulate SRDs. The trick would be to accurately characterize real candidate parts (I'm talking 10s of amps and kilovolts here) then tweak the sim to behave like them.

--
John Larkin         Highland Technology, Inc 

jlarkin att highlandtechnology dott com 
 Click to see the full signature
Reply to
John Larkin

Yeah, so does the fristor give you a way to control the large I or V? Suck the energy off into a power supply rather than a resistor.

I don't have any use for this at the moment. The closest is killing a large DC polarizing current in an Earth's field NMR coil. Done with a FET, resistor and Zener, f~3kHz. But you've got to kill it faster than that or the spins can follow the field.

George H.

Reply to
George Herold

Well the energy has to go somewhere. Where does it go?

George H.

Reply to
George Herold

So what does it take to have a power supply both give and receive energy? Sure a battery does that. Is there away to do it electronically?

George H.

Reply to
George Herold

Well, you're back to the EE101 dilemma of opening the connections to an inductor when there's current flowing. Barring parasitics, the inductor voltage is a unit impulse. The energy magically vanishes in zero time. We're not physicists, so we don't worry about stuff like that.

--
John Larkin         Highland Technology, Inc 

jlarkin att highlandtechnology dott com 
 Click to see the full signature
Reply to
John Larkin

A fristor can be dissipative; make it out of depletion fets or something like that.

Does it ring? An RC damper might help.

--
John Larkin         Highland Technology, Inc 

jlarkin att highlandtechnology dott com 
 Click to see the full signature
Reply to
John Larkin

No, by definition. the only possible exception being a superconductor.

--
umop apisdn 


--- news://freenews.netfront.net/ - complaints: news@netfront.net ---
Reply to
Jasen Betts

zener's aren't considered passive by most.

If you're only ever charging it a battery is as passive as a zener.

--
umop apisdn 


--- news://freenews.netfront.net/ - complaints: news@netfront.net ---
Reply to
Jasen Betts

On 20 Sep 2014 02:03:50 GMT in sci.electronics.basics, Jasen Betts wrote,

How do you build an amplifier out of one?

Reply to
David Harmon

a zener at very low bias will oscilate.

--
umop apisdn 


--- news://freenews.netfront.net/ - complaints: news@netfront.net ---
Reply to
Jasen Betts

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.