Re: International standards (2023 Update)

The HT7660 is speced for an absolute maximum input of 13 volts, the lt1044 for 9.5 volts, and the TC7660 for 10.5 volts. So, maybe, but doubtful.

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John Popelish

Hello

What's the best (easiest) way to double a 9V DC supply to 18V DC? The 9V comes from a 78L09 regulator. The current requirements are very low. Do any chips exist to do it? I'm an electronics novice so the simpler the better.

Thanks.

Best idea I can come up with without using separate *real* dimmer circuits for aech string is that which you don't seem to want to hear. I don't know what picaxes can do, but if you can get a single pwm output, you can and that with the on signal. 7 outputs... like so:

| __ ||-+ +----| | ||

They still do in many cases. I think some of them got tired of it and just skip it.

I got tire of that. I found out all the sales dweeb has to do (at that time, but they still can and don't even argue with me) is hit the esc key and that gets him out of the junk mail screen.

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Best Regards,
Mike

Hi, I'm converting an HID Nissan Altima headlight into a light that you can plug into a wall outlet, but I'm having trouble finding the ballast I'll need to do this, any help? Thanks.

Get a 12 volt DC power supply at whatever the current the lamp draws. If it'll work on AC get a 12 volt transformer. When I was a kid I used a toy RR transformer to power the unburnt half of a 6 volt auto headlight and used it as a search light.

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can

Sounds like a rx shielding problem and the need for a high pass filter.

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out

filter

is

Would it make more sense to supply the doubler with the same raw DC as the 7909 is getting?

Thanks, Rich

2 ens and 2 els, but I think I had his home page right. Should find links there, but ECADEList.html or htm looks right.

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Best Regards,
Mike

Good question. He mentioned that turning on one string causes them all to turn on under whatever incarnation of the circuit he was talking about. IIRC it was the one with the gd cap.

^^^^^^^^^^^^^^^^ add a hyphen or two and readers will clip your title block for replies.

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Best Regards,
Mike

Greetings.

I believe "PinelL" has two els, and that the web page you were thinking of is the following:

These are just my beliefs: I may be misguided.

Cordially, Richard Kanarek

I see, so "power follower" is "power emitter follower". R1 is a bit strange for an emitter follower, and no biasing for T as well , but I do see what you mean.

Thanks. More questions coming up, as the documentation of the lm317 is full of circuits which seem to be good to know.

How do I find the gain for the High Gain Amplifier in the manual of the lm317 page 16

Assuming we have a load RL from the output to ground can we say the following:

IL = Vo/RL where Vo = output current, IL = load current

Denote the constant current of the regulatror as C

C = Ic + IL , where Ic = collector current

Ic = Ib * beta hence Ic = Vi/R1 * beta where Vi = input voltage

all of this gives us

(Vo/RL) + (Vi/R1)*beta = C

what is the gain ?

How are you arranging the 5V logic supply? Battery?

Regards, Bob Monsen

I've been testing my line with a dsl router that I have. I would like to know if there is a simple circuit that I could put together that could increase the attenuation about 20 dbm. Connected to the frame in the Central Office I get about 8 dbm I would like around 28 dbm. Is there a simple way, for instance connecting 2 capacitors in series. The phone line carries around 48-51 volts DC. I know it sounds strange adding attenuation in this case, but I'm curious if it could be done artificially instead of just being dependent on the distance. If I test about a block down the street I get about 4 dbm more. Any help would be appreciated.

I suspect it is included as part of the input current limit if the LM195 goes into any protective shut down. This would not much apply to an ordinary transistor.

Most emitter followers (except for push pull complementary designs like LM6121:

) do not correct for temperature shift in the base emitter drop.

You might also look up the data sheet for the LM195, to understand more of the function of the follower.

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John Popelish

I am upgrading a circuit I inherited... a controller with an ADC to measure various DC voltages (0 - 2.5VDC). The analog nets are liberally sprinkled with 1uF Tantalum capacitors to ground , obviously trying to dampen noise. My questions:

why polarized? Why tantalum? Why 1uF?

I am trying to migrate to SMD technology and find to my surprise that SMD TA caps are rather expensive (unless I am reading the Mouser catalog wrong). So I am looking for possible (cheaper) alternatives or convincing justifications. The original board had serious digital to analog noise problems (no single ground point, noisy ADC Vref) so I am guessing that all these caps may not be needed at all or could be changed to something tame and cheap. Plus, I'm smoothing in SOFTware ;-)

The 5v supply is derived from the 35v AC input using a typical transistor/zener arrangement. Transistor is MJE3055, zener is 5.1v. Output sits on 4.8v with almost no ripple on scope.

Rectifier > 1000uF 63V cap to gnd > MJE collector > MJE emitter >

100uF cap to gnd > PIC and 595's. Zener between MJE base and gnd. 10k resistor between collector and base.

If you need something right away, and the chips mentioned by other posts aren't available, try a 555-based voltage doubler. If you use a 555, you'll need 2 more resistors, two extra diodes and one extra cap:

Good luck Chris