Re: Towards the autonomous lifter - electrostatic voltage generators.

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Malcolm Watts" <m.j.watts@xxxxxxxxxxxx>

Diode weight and number to could be kept down by (a) generating a
high voltage to begin with (not difficult) and (b) using passivated
EHT diodes (e.g. Philips BY712) encapsulated in heatshrink (done it a
number of times and it works well). I built a 4 (5?) stage multiplier
once which put out a spark of about 2".

Malcolm

On 2 Jul 2005, at 0:06, Tesla list wrote:

> Original poster: Robert Clark <bobbygc2001@xxxxxxxxx>
>
>  > This might be workable using Cockcroft-Walton
>  > voltage
>  > multipliers to get the high voltage required. This
>  > would eliminate the need for many batteries
>  > connected
>  > together and also the need for a transformer. The CW
>  > multiplier is also light-weight consisting just of
>  > diodes, capacitors and wires.
>  >  However, I estimated given the power and the weight
>  > of lithium polymer batteries and assuming a 1g/1
>  > watt
>  > lifting capability of a lifter, the batteries would
>  > only be able to lift their own weight for a few
>  > minutes before they became drained.
>  >  For instance using the TP4000-8S2P battery with the
>  > specifications below, at 29.6 volts and 4000 mAh,
>  > this
>  > gives a power rating of 29.6V x 4 Ah = 118.4
>  > watt-hours. But the battery itself weighs 656 grams,
>  > so assuming a 1 g/1 watt lifting capacity, it could
>  > lift its own weight for 118.4/656 = .18 h, or about
>  > 11
>  > minutes. This is not even considering the weight of
>  > the lifter. The CW multiplier would probably be only
>  > a
>  > small portion of this.
>  >  From Blaze Labs examples we might expect the lifter
>  > body to be about the same weight as the payload
>  > (which
>  > here includes the power supply), so about 656 g.
>  > Then
>  > the battery would be able to raise the lifter and
>  > battery for less than 5.5 minutes.
>  >  Nevertheless, it would be great if someone did this
>  > to prove a lifter could raise itself under it's own
>  > power if only for a few minutes.
>  >
>  >
>  >   Bob Clark
>  >
>  >
>  >  TP4000-8S2P	
>  >  Amp Hours: 4000 mAh
>  >  Voltage: 29.6V
>  >  Balancer connectors
>  >  Rating: 10-12C continuous, 20C (80A) burst
>  >  Output: 29.6V Nominal, 4000mAh
>  >  Dimension: 50mm x 245mm x 28mm
>  >  Weight: 656 grams	
>  >  Retail: $349.95
>  >
>  >
>
> I wanted to save weight by eliminating the
> transformer. But it may turn out the large number of
> components for a kilovolt CW multiplier without
> transformer would cancel out the weight savings. I
> discussed this in a post to www.powerlabs.org copied
> below. A question I would like to see answered is what
> is the weight for a microfarad capacitor?
> The post refers to the 555 oscillator IC. I needed
> that because the CW requires AC while the lithium
> batteries put out DC. The 555 provides a simple
> lightweight method for converting DC to AC:
>
> DC to AC Inverter with the 555.
> http://www.uoguelph.ca/~antoon/circ/555dcac.html
>
>
>    Bob Clark
>
>
> Post to www.powerlabs.org:
>
> *************************************************
> RGClark
> Joined: 11 May 2005
> Posts: 20
> Posted: Fri Jul 01, 2005 9:48 pm
>
> ...
> You're right about the problem of getting up to
> kilovolt ranges. I wasn't taking into account the size
> increase of the CW circuit in relation to the voltage
> multiplication. For instance this page shows you need
> to increase the number of stages to increase the
> voltage multiplication:
>
> Cockroft Walton Voltage Multipliers.
> http://home.earthlink.net/~jimlux/hv/cw1.htm
>
> This also shows a transformer attached at the
> beginning. I wanted to eliminate the transformer to
> save weight. But this might result in an impractical
> number of stages.
> For instance, this lithium battery puts out about 30
> V:
>
> TP4000-8S2P
> Amp Hours: 4000 mAh
> Voltage: 29.6V
> Balancer connectors
> Rating: 10-12C continuous, 20C (80A) burst
> Output: 29.6V Nominal, 4000mAh
> Dimension: 50mm x 245mm x 28mm
> Weight: 656 grams
> Retail: $349.95
> http://www.thunderpower-batteries.com/html/batteries.html
>
>
> Let's say we use 100 CW stages to multiply this to
> about 3,000V. How much would 100 diodes and capacitors
> add to the weight? Would we be better off just using a
> transformer?
> Actually I'm not even sure 3000V would be enough
> voltage to raise a lifter. You might actually need
> 1,000 stages(!) Also, the "Cockroft Walton Voltage
> Multipliers" page mentions the voltage loss as the
> number of stages increases.
> However, the page also mentions you can reduce the
> losses by using high frequency AC. So perhaps instead
> of the standard 60 Hz AC, we could use an AC source in
> the thousands of hertz range. This page shows the 555
> IC can operate in the kilohertz range:
>
> 555 timer IC.
> http://www.doctronics.co.uk/555.htm
>
> And this page suggests the frequency for the 555 can
> range into the megahertz:
>
> 555 Timer Tutorials.
> http://www.williamson-labs.com/555-tmg-charts.htm
>
> According to the diagrams on the first page, it's just
> a matter of choosing the resistors and capacitors
> attached to the timer to change the frequency.
>
> This page by Blaze Labs discusses use of the CW
> multiplier and calculates the voltage loss for an
> example 3-stage CW multiplier:
>
> Experiment 15 - Cockroft Walton Multiplier.
> "The voltage drop under load can be calculated as:
>
> VDROP = [Iload/(6fC)] * (4n^3 + 3n^2 - n)
>
> where:
> Iload is the load current (Amps)
> C is the stage capacitance (Farads)
> f is the AC frequency (Hz)
> n is the number of stages.
>
> Example: A 3 stage CW, driven by a 70kHz peak voltage
> of 10kV, with capacitors value 390pF, and a load
> current of 10mA:
>
> VDROP = [Iload/(6fC)] * (4 n^3 + 3 n^2 - n)
> VDROP = 8kV
> Eout = 60kV - 8kV = 52kV"
> http://www.blazelabs.com/e-exp15.asp
>
> This loss of 8kV is only for 3-stages where I'm
> envisioning hundreds of stages. For this to work, I
> would need both much higher frequency and much higher
> capacitance. Notice the capacitance in this example is
> only 390 pF. But small capacitors exist at a million
> times that, i.e., in the microfarad range. You could
> also make the 555 run at say 1 megahertz instead of
> the 70kHz in this example.
> However, as shown on this page the larger microfarad
> capacitors are the heavier tubular kind rather than
> the lightweight flat kind:
>
> Capacitors.
> http://www.kpsec.freeuk.com/components/capac.htm
>
> So you still have the question of the weight of the
> hundreds of capacitors required.
>
> In regards to the thrust to weight ratio, here are
> some examples from Blaze Labs showing approximately 1
> gm/1 watt thrust to power ratio:
>
> Super V1.0 cell - 15/04/03
> http://www.blazelabs.com/l-c-superv1.asp
>
> Experiment 14 (21/03/03)- 100g payload lifter.
> http://www.blazelabs.com/e-exp14.asp
> *************************************************
> http://www.power-labs.com/forum/viewtopic.php?p=3815
>
>
> ->Terry notes - If they are going to power their lifters with a Tesla
> coil, it is probably on topic... <-
>
>
>