Re: International standards (2023 Update)

Generate a supply limited square wave, couple to a voltage doubler (3 diodes + 3 capacitors) sitting on top of the + supply . O/P = 9V + 2X9V

- volt drops minimised by using schottky diodes. Regulate o/p down to 18V.

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ddwyer

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Do a web search on "RF modems". There are a lot of companies that make fairly inexpensive units. You could use a cheaper PIC, and output RS-232 into an RF modem linked to your PC. As a bonus, your PC could also talk to your PIC and do any kind of control you might need.

John

In response to what John Schuch posted in news:_64Rc.12012$ snipped-for-privacy@newsread2.news.pas.earthlink.net:

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Joe Soap.
JUNK is stuff that you keep for 20 years,
then throw away a week before you need it.

A high side switch would do the trick, but the BS108 is probably not the device to use. You would have to pull its gate a few volts above the 9 volt rail to turn it on.

I would try a PNP transistor (emitter to +9, collector to 7660, 10k base to emitter) driven by a common base NPN (base connected to the

+5 rail, emitter driven by active low logic through a current limiting resistor that sets the output current, collector to base of PNP). Do you have any small PNP and NPN transistors available, like 2N3904, 2N3906, etc.?

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John Popelish

Hello,

I have a 7660 DC-DC converter which I would like to turn on and off from a microcontroller. The microcontroller runs at 5V and the 7660 runs at 9V (it doubles 9V to 18V). I was thinking of using a transistor to do this. In particular, I was hoping to use a BS108 transistor as its the only type I have. My questions are:

1) Will this transistor be able to do what I want? 2) I was going to connect the emitter to ground and the collector to the ground of the 7660. The V+ pin of the 7660 would then goto the 9V supply. Is this the correct way of doing it? 3) What value resistor do I use on the base of the transistor? Does the value really matter? 4) I have more than 1 BS108 transistor, so I could make a darlington pair. Would this be better? If so, how do I wire it up?

Thanks for any help.

Without knowing anything about your particular system, I will point out that DMMs are relatively insensitive to interference and noise that is synchronous with the power mains, since they average over an integral number of powerline cycles. Your A/D may be reading mains hum at 60 Hz, but asynchronously so that it doesn't hit the same phase each time. If you can adjust the timing of your A/D readings to be nearly an integer multiple of the

60 Hz period, see if the variation in readings slows way down or stops as you get in phase with the line.

Hope this helps!

Bob Masta dqatechATdaqartaDOTcom D A Q A R T A Data AcQuisition And Real-Time Analysis

"Zucker" skrev i melding news:rQPQc.21183117$ snipped-for-privacy@news.easynews.com...

clock

the

single

I beleive you have to use a delay circuit. The button itself must be conected to the up/down pin on the counter directly (no delay circuit between). The delay circuit must stay between the button and the clock-input of the counter.

Geir

sometimes you can use a trick.

Vo = -Vx * R2 / (1/sC2)

I1 = current through R1 = Vx/R3 + Vx/(1/sC2) + (Vx-Vo)/(1/sC1)

Vi = Vx + R1*I1

solve the first equation for Vx Vx = -Vo/sRC2 substitute that into the second equation I1 = (-Vo/sRC2)/R3 + (-Vo/sRC2)/(1/sC2) + (-Vo/sRC2 -Vo)/(1/sC1) and put that into the klast equation

Vi=Vx+R1*[ (-Vo/sRC2)/R3 +(-Vo/sRC2)/(1/sC2) +(-Vo/sRC2 -Vo)/(1/sC1)]

snipped-for-privacy@aerojockey.com (Carl Banks) wrote: [snip]

Does exactly what it says on the tin.

Tim

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Google is not the only search engine.

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I

supply.

pair.

Thanks for the reply.

I was hoping that the 18V output would go to zero. If I connected the source to the V+ pin of the 7660 and the drain to the 9V supply, would that allow me to turn the 7660 device completely off?

I've just completed building a fairly long sail boat, a radio-controlled boat, which is to be powered by both batteries and solar panels, along with the help of the wind. I'd like to use separate flexible solar panels, they are extremely light in weight, to power one small DC fan and one bigger DC fan. Here are the specifications of those fans: small fan (Rated Voltage: 12VDC, Rated Power Current: 0.15 Amp, Rate Power Consumption: 1.8 W); big fan (Rated Voltage: 12VDC, Rated Power Current: 1.0 Amp, Rate Power Consumption: 12.5 W). These fans will be placed in a way that they blow air at the sails, thus propelling the boat. I would like to sail this boat for 5 hours non-stop.

My question: based on the specifications of the fans, what are the sizes for the solar panels (in terms of Rate Power Consumption) for the small fan and the big fan? Thank you.

John.

What's assumptions (if that's the right word) do we make to justify using that trick?

In the mean time, I'll try simplifying the above and BTW, I'm trying to come up with those formulas, above, one way or the other.

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Best Regards,
Mike

What signal is carried by Cable TV? Is it VHF, UHF, anti-protons (lol)?

Where I'm living now, I cannot possibly throw a cable to my room, so I am considering building a transmitter/receiver of CATV, if that's even possible economically for domestic use.

Does anyone know where I can find such circuits?

Thanks in advance.

The first two.

If you mean you want to broadcast CATV to your rabbit ears and loop, don't. The mid-band is shared with aviation and the CATV copany does leakage checks. You'll be interfering with peoples off air reception (which is on a different channel line up) and ghosting the CATV signal of others who may have leakage (ingress.)

The line amps at home depot and such give varying degrees of signal quality and the ones outside on the line start at $700 or so and require a special power supply.

*Why* can't you run a cable to your room.

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Best Regards,
Mike

Thanks for the replies.

The chip is an ST TSH10 single wideband opamp.

offset

If I was laying this out and concerned about noise pickup on the offset pins, I would put a small island connected to V- under pins 1 and 8. If I could fit a trace between those pins and the adjacent ones, I would do that and connect it to V- also. That would keep the output or V+ from coupling to those pins and help keep the V- rejection at maximum.

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John Popelish

Your sail should be a vertical cylinder, which you spin around it's vertical axis.

Oh, I wasn't sure :) I'll look at that, but I was trying to figure out if I had the problem set up right so I could derive the

*Laplace* xfer function, myself.

What is wr? 2.pi.f ? What about P and Ar?

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Best Regards,
Mike

I'll repost in sed.

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Best Regards,
Mike