Switch Question / High Voltage / Forums

Forums

4hv.org :: Forums :: High Voltage

« Previous topic | Next topic »

Switch Question

first previous 3 4 5 6 next

Move Thread

LAN_403

GammaRay

Mon Nov 19 2012, 02:39PM

Registered Member #5323 Joined: Fri Jun 15 2012, 02:14PM
Location:
Posts: 104

C1=22,000 uf (M) 63v Epcos P/N B41560-A8229-M

Using 3 Sidacs in series, each Sidac rated at 240-280 VBO @ 1A, by Littlefuse P/N K2500G

appears to be a total of about 800 volts. Alternatively can use an 800 volt gas-filled spark arrestor by Epcos #506, which sparks at nearly the same Hz as the 3 Sidacs. Here is the data sheet for the arrestor

Newton, here's the part I am not pleased to say, upon closer inspection, I discovered another faded "0" on the C2 HV cap (its pale black writing on a dark brown pancake cap) so the actual value of C2 is 10,000pf @20kV. My apology as I see the amount of calculations you have already done. Matt, I tried using the reed switch at the beginning but found they sparked irradically compared to the gas filled spark arrestor, however, I have others from a different vendor I can try.

Antonio

Mon Nov 19 2012, 03:13PM

Registered Member #834 Joined: Tue Jun 12 2007, 10:57PM
Location: Brazil
Posts: 644

Normal reed switches spark at about 1000 V or less. I have tried one as spark gap in a similar application. But don't believe in the low leakage of the glass. It must be very clean and dry. If you just touch the surface the leakage jumps to many uA easily.

Tony Matt

Mon Nov 19 2012, 10:22PM

Registered Member #3700 Joined: Sat Feb 19 2011, 12:59PM
Location:
Posts: 107

Hi Antonio ,
Wath could be an arrestor that disrupt at 1000Vdc and has an insulation more than 200megohms?
Regards
Tony

Antonio

Mon Nov 19 2012, 10:53PM

Registered Member #834 Joined: Tue Jun 12 2007, 10:57PM
Location: Brazil
Posts: 644

A reed switch, a large one, works. It must be clean and dry. It's also possible to make an adjustable open spark gap using screws with rounded points mounted on plastic supports.

Newton Brawn

Mon Nov 19 2012, 11:14PM

Registered Member #3343 Joined: Thu Oct 21 2010, 04:06PM
Location: Toronto
Posts: 311

Recalculating... AGAIN ...AGAIN!

The current that charge the C2 capacitor (0.01uF) from 0 to 1000 volts in half second:

I = C* dv/dt = 0.01*0.000001 *1000/0.5 = 2microampere

SOoo
The capacitor C2 charging time is 0.5 second.
The antena charging current goes to the capacitor and to the leaks.
The ammount of the antena current that feed the capacitor is 2microamperes

The C2 discharging current through L1:

Charecteristic impedance C2 with L1:
Zo = (L/C)^1/2
Zo = (0.012 /(0.01 x 0.000001))^0.5 = 1095 ohms
Peak Current = Ec/Zo
Peak Current = 1000/1095
Peak Current = 0.9129A.

And the discharging time (not considering the LED and C1)
t= (L*C)^0.5 = 0.012 *0.01*0.000001)^0.5 = 11microseconds
( the frequency is 14.5 kilohertxz) (In your broadcast radio you may have a click every 14.5 kilohertz

Energy in a 0.01uF cap charged to 1000V:
E= 0.5*C*V*V = 0.5*0.01*0.000001*1000*1000 = 0.005joules or 5milijoules.
This 5milijoules are tranfered to the coil during the discharge.

The energy also may be calculated as E=Ipk*E*t/2
E=0.912*1000*11*0.000001 = 5.016milijoules

Now:
You said that "If I look very closely at the led, I can indeed barely see a slight brightening ...in perfect sync with the sidac discharges"

This info let me assume (nice gest) that the led is feed with 2volts and 2miliampere during 0.2second...

If your LED blinks with 2volts and 2miliampere during 0.2 second, the LED energy may be;
Eled= 2*0.002*0.2 = 0.8milijoule.

Conclusion: The energy of the capacitor is reasonable tranfered to the led.

Well, the nest step is Gammaray try to increase and reduce the value of C1 and inform how is the glow of the led.
Gammaray to try 11000uF, 44000uF and report the led reaction. My gess is 11000uF will work better.

Tony Matt

Tue Nov 20 2012, 03:01PM

Registered Member #3700 Joined: Sat Feb 19 2011, 12:59PM
Location:
Posts: 107

Hi Gammaray,
Try replace C1 for a 500, 1000 and 2000 uF Informe the result.
Eliminate the 1000 ohms shunt resistor.
Cheers

Tony Matt

Tue Nov 20 2012, 05:35PM

Registered Member #3700 Joined: Sat Feb 19 2011, 12:59PM
Location:
Posts: 107

Please see next

Tony Matt

Tue Nov 20 2012, 07:49PM

Registered Member #3700 Joined: Sat Feb 19 2011, 12:59PM
Location:
Posts: 107

Hi
Here are 3 options:

#1 - 200Vdc breakdown, glass14x2.2mm, 200Vdc breakdown, 10gohm, rated 180Vpk1,25Apk

#2 - 200Vdc break down, glass17x2.8mm, 200Vdc breakdown, 1gohm, rated 100Vpk0.5Apk

#3- 500-600Vdc breakdown, glass21x2.7mm, 500Vdc breakdown, 10gohm, rated 350Vpk0.5Apk

GammaRay

Tue Nov 20 2012, 08:04PM

Registered Member #5323 Joined: Fri Jun 15 2012, 02:14PM
Location:
Posts: 104

I measured the output of the circuit with C1 at 500, 1000, 3300, 6600, 10800, 50000, & 100000 uf, with and without the 1k led resistor. The measurements were taken at C1. To summarize the results on tests made with the 1k, at all values of C1 the voltage settled at between 2.90v and 2.91v, although at the lower uf's it swang up and down a good bit, I averaged out the reading. With the larger uf's, the output became more steady. The cap values tested resulted in same output V after each cap was charged. To summarize on tests made without the 1k resistor, at all values of C1 the output settled at 2.46v-2.47v once the caps were charged and the led was much brighter. The output voltage seemed to average out to the same reading (regardless of cap value) once the caps were charged (I averaged the big swings of the smaller ufs). I suppose an advantage of the larger caps is that the output is smooth DC, with the small caps, its choppy DC. About the reed switch, I tried the larger version (even washed it squeeky clean), however, it tends to fire somewhat randomly in my circuit, doesn't quite result in as good an output as the spark arrestors or sidacs for some reason. I'm still all ears about what next to try :)

Newton Brawn

Wed Nov 21 2012, 11:03PM

Registered Member #3343 Joined: Thu Oct 21 2010, 04:06PM
Location: Toronto
Posts: 311

GAMMARAY,

You wrote:

"""with C1 at 500, 1000, 3300, 6600, 10800, 50000, & 100000 uf, with and without the 1k led resistor. The measurements were taken at C1. at all values of C1 the voltage settled at between 2.90v and 2.91v, """

Weel, weell..
2.9 on a 1k resistor results in a 0.0029 mA.
The power dissipated by the resistor will be P= ExI = 2.9x0.0029 = 0.00841watt
As we calculated before, the capacitor C2 discharghes twice per second, and each discharge delivers 0.005joule,
in other words the energy deliverid by C2 in a second = 2 x 0.005 = 0.010joules per second = 0.010watts ....

Your machine has a efficience of 0.00841/0,01 = 0. 84 or 84%

That is very good!

Also,
""" To summarize on tests made without the 1k resistor, at all values of C1 the output settled at 2.46v-2.47v once the caps were charged and the led was much brighter.""""

I woud like to see the LED flashing
Found a C1 capacitance that produse a nice bright flash, and post a picture, or if is possible post a video !

Regards

Newton

first previous 3 4 5 6 next

Moderator(s): Chris Russell, Noelle, Alex, Tesladownunder, Dave Marshall, Dave Billington, Bjørn, Steve Conner, Wolfram, Kizmo, Mads Barnkob