Beginner in need of Help!

Be more specific.

If the it's DC-current and voltage below 30V, you can use a comparator.

Find a point in your cuircuit where the voltage vary with the current and connect it to one of the inputs. (If you can't find any put in a low value resistor serial.) Connect a fix voltage to the other input and you will have your signal on the Output switching between open and ground depending of the current.

Good luck /Frederik

"James" skrev i meddelandet news:SQGoh.25690$ snipped-for-privacy@newsfe6-win.ntli.net...

"James" wrote in news:SQGoh.25690$ snipped-for-privacy@newsfe6-win.ntli.net:

As Fredrik said, look at a comparator. (Or any cheap standard op-amp).

Also, look at discrete active components, the transistor, FET, thyristor and triac. Any one of those might be suitable. By the time you understand each of those well enough to choose the most suitable and apply it to your problem, you won't be a beginner anymore. it won't take you very long to work it out either, the more references you find online and can grasp quickly (pass over those that look opaque, there are are always other opinions and guides), the faster you'll grasp the rest and know which ones are useless to you.

What I want to achieve is hard to describe but I'll try. Say I've got a v simple circuit that includes a power supply and a bulb. I break the circuit and want to put something in its place - this component would measure the voltage and, providing it was in-between set boundaries (i.e. between 0.4V and 1.2V or between 2.4V and 2.8V) would complete the circuit. If the voltage was not within ranges specified, the circuit would remain broken. I hope this is clearer :o)

James

a

going

How can it sense the voltage without applying voltage?

Is this something to do with cycling ni-cads for RC Models?

-- Graham W

PGM-FI page updated, Graphics Tutorial WIMBORNE Wessex Astro Society's Website Dorset UK Info, Meeting Dates, Sites & Maps Change 'news' to 'sewn' in my Reply address to avoid my spam filter.

you need something called a voltage comparator. look it up. they come in various forms. the LM311 is a comparator that works ok. op-amps also can work as a comparator how ever, some op-amps have full backs depending on how complex you get and what you expect over all.

--
"I'm never wrong, once i thought i was, but was mistaken"
Real Programmers Do things like this.
http://webpages.charter.net/jamie_5

______ V+ ----A B-----+ | [Bulb] | Gnd --------------+

What you described means the circuit must sense the voltage between points A and B. You *don't* want to do that - your description is not correct. Every time you close the contacts that connect A to B the voltage between them drops to 0 and your sense circuit can no longer determine whether the contact should remain closed or should open.

What you *do* want to do is sense the voltage between V+ and ground. When that voltage is within a specified range, you want points A and B connected.

You can use a window comparator to meet the above requirement. I think you want more detail than just the words "window comparator", but more detail on the requirements is needed to do that. What is the load current? What is the maximum range of V+ ? What are you trying to do? Someone replied suggesting you might want to discharge a NiCd - if that is the case, say so.

Ed

What I really want to do is be able to send a digital signal (via means of a series of switches on a control box) through a series of parallel circuits each containing one lamp. Each corresponding signal or absence of a signal (data) would then either allow or not allow power to the lamp (power.)

see

epic.jpg

Is the need for a digital set of electronic pulses what differentiates a digital electric circuit from an analogue electric circuit? How can this be accomplished with this circuitry?

I hope this is clearer

v

circuit

the

0.4V

broken. I

"James" wrote in news:O6Uph.59507$ snipped-for-privacy@newsfe5-win.ntli.net:

From my earlier post:

Look at discrete active components, the transistor, FET, thyristor and triac. Any one of those might be suitable. By the time you understand each of those well enough to choose the most suitable and apply it to your problem, you won't be a beginner anymore. it won't take you very long to work it out either, the more references you find online and can grasp quickly (pass over those that look opaque, there are are always other opinions and guides), the faster you'll grasp the rest and know which ones are useless to you.

Specifically, look at the use of an NPN transistor on the ground side of each load (lamp, in this case). It's a cheap, easy, standard method of making a small signal (digital or analog) control a low-voltage DC load. Look at the use of a transistor as switch, rather than as gain stage.

You want an X-10 system. Google X-10. It works by placing digital addresses and commands on a 121 kHz signal which is placed on the AC mains.

For your other question:

Ed

If you just want several switches to individually operate several lights, (switch one turns on light one, switch two to light two...) there is no logic required - just connect each switch in series with its corresponding light, and connect all the switch/light pairs in parallel across the power supply - see

--
Peter Bennett, VE7CEI  
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No. Are you trying to build a "Magic Switchboard"?

I need all the switches to be located in one place

of a

circuits

signal

l

be

Does such a component exist?

of

circuits

signal

James skrev:

Yes, get it at the Magic Shop.

--
Hilsen Mikkel Lund
"Sund fornuft, har aldrig stoppet en tosse"
Jokeren i "Mænds ruin"

haha

If you looked more closely, you'd see I was after a circuit that would be able to handle digital signals.

means

a

this

"James" wrote in news:sb9qh.83298$ snipped-for-privacy@newsfe4-gui.ntli.net:

We looked plenty close, and gave you a magic potful of wrong answwers. What's really funny is none of us are to blame. You're going to have to spill the whole story of what you want, partly to frame the concept to yourself so you have a clearer idea of what to ask, then to ask so you get meaningful answers. So far you've been suggested a set of switches in paralel, through transistors, op-amps and comparators, and a full-scale digital system modulated onto the AC line, and we don't even know if you're wanting your mains lamps switched, or a set of torch bulbs on a wodden board for an educational project, because you won't tell us. And unless you do, people will start to wonder if you're a troll baiting people into looking like fools by sounding like they know the answer to a question that was never really asked.

Please "bottom post" - place your reply below the message you are replying to, and trim any unnecessary quoted material - thanks.

So - put all the switches and the power supply in one place, and run a pair of wires (power from switch, and return to supply) to each light

- no electronics required. If all the lights are in one place, a single return wire may be adequate, depending on the current drawn by the lights, and the operating voltage.

If you have something more complex in mind, please give us more details of your requirements. The better you specify the problem, the more likely we will be able to give a useful answer.

How many light/switch pairs are there? Are all the lights also in one place? How far from the switches to the lights? What type/voltage/power are the lights?

--
Peter Bennett, VE7CEI  
peterbb4 (at) interchange.ubc.ca  
new newsgroup users info : http://vancouver-webpages.com/nnq
GPS and NMEA info: http://vancouver-webpages.com/peter
Vancouver Power Squadron: http://vancouver.powersquadron.ca