Sorry the last post was so long thanks to anyone who answers it.
Here's another simpler one.

I'm creating a toggle switch for a fan and a few other things. The
current going trough the line I'm switching is way too high for any
led. So how can I rig an LED to light up when the switch is closed?

Also unrelated, would 2.4V kill an LED from Radio Shack that boasts a
2.1 Vf?

Thanks all,

Jay W

Hey Guys, I'm new here and have only very basic
knowledge of electronics. I have several wiring
projects going on with my truck and will ask mostly
that. See a little bio at the end.

I saw some post from last month about LEDs to a 12V
source and want to expand on this.

The first thing I want to build is my own LED
tail/brake lights for my truck, I don't like the
comercial ones, and their too expensive. Also I want
to build some LED front marker (blinker) lights.

If some one knows these auto systems better than I
describe then please chime in.

There are two problems I have. 1.) Both the front and
rear need to have both a low light and bright light
setting. Low for lights on, bright for blinker or
brake operation. The voltage sources I have to work
with are two 12V lines. One operates with lights on
and both are active with blinker/brake operation. The
best idea I came up with is to hook normal LEDs to the
"lights on" source and super-bright LEDs to the
"brake/blinker" source. This would light up several
low light leds for lights on, and light up several
bright leds plus the low light leds in brake/blinker
operation. Does anyone have a better idea??? I'd
prefer to use all bright LEDs because they are clear
when not on.

2.) With LEDs in place of a incandesent bulb the
blinker relay will think there is a problem and go
into "blink fast" mode. This is no good to me. I
know nothing about blinker relays, can anyone help me
with this. How can I modify the relay or line to not
detect a problem. I'm guessing that the relay is
detecting a low current when it expects a high one.
So if I got desperate I could try to dump a lot of the
current through a circuit, but this seems like a waste
of watts, and I'd have to come up with cooling
solutions. Any help would be highly appreciated.

Bio Info.

Name:
Jayson Woodruff

Location:
Orange County, California

Job:
Rocket Scientist (no joke)

Hobbies:
Mountian/Road Biking (and repair), Truck racing and
showing, soon to be racing a tiny little fiat.

Annoying Habits:
Tend to be long winded.

Jay W



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The only specs that i need to meet is I need to keep my a/c freq. in
tact after upping the voltage. I picked up a lm741 from radio shack
and I will try it. Is there a reason you say to use closed loop mode
I was going to use non-inverted mode????

thanks
--- In Electronics_101@y..., Himanshu Sharma <hs_ramdev@y...> wrote:

Hi ,

I hope that Op-amp will work great in this
case...

Or is there any thing you want specific...

If not read the data sheet of 741 used in
closed-loop-gain mode...

Regards

=====
Himanshu Sharma Ramdev

URL:

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Messenger

Hi ,

I hope that Op-amp will work great in this
case...

Or is there any thing you want specific...

If not read the data sheet of 741 used in
closed-loop-gain mode...

Regards

=====
Himanshu Sharma Ramdev

URL:

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Anyone have an idea for a low voltage a/c amplifier to use for input
into a freq to voltage converter. My input is 1-8mv a/c and I need
to bump it up to a min of 1volt and a max 28volts. Anyone with a
simple solution.

Thanks

Hi

Try and learn about how a 555 IC works as that
will solve the problem for you...

If you have enough time then I can make the
circuit for you.......

when the door opens the alarm will be ON;
at a push of a buton the alarm will be OFF for
a period of time (let's say 30secs... up to
1minute) and afther that time period the alarm
should go ON by herself... and so on... until
the door will be closed... when it will be
completly OFF or at least in StandBy.

just to make it easy let me tell you that main
power supply will be maintained by a switch at
the door...
Now when the door will open the ring will go
on.. the other switch will be connected to a ckt.
made up of 555 which will send the necessary time
delay when the switch is pressed.

Hope you got that.....

Regards


=====
Himanshu Sharma Ramdev

URL:

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You can convert a ring counter to a johnson counter by aiming a gun at his head and smooth talking him.

<html></html>

From: thecrack@...
Reply-To: Electronics_101@...
To: Electronics_101@...
Subject: [Electronics_101] Re: Shift-register and synchronous counters
Date: Thu, 23 Aug 2001 06:26:48 -0000

--- In Electronics_101@y..., thecrack@t... wrote:

--- In Electronics_101@y..., adityan007@y... wrote:

the answer is 11
because 2 raise to 11 =2048
but 2 raised to 10=1024 which is less than 1500

Thankx

But can you please explain in more detail? You see I am new in this

world of

electronics and unfortunately I have to ask people like yourself to
get all the answers.
Another question:
How can a ring counter be converted to a Johnson counter?

Still no one out there that can help me?
Please I really need some help here. If this is the wrong group let
me know so that I can browse more for one that can help me.

Thank you

Jon

Thanks for the support:

Here is the question:
A counter is neede to count the number of cans passing on a

conveyor

belt. A pulse is generated each time a can passes a sensor,

which

in

turn triggers the counter circuit. The counter needed has to

count

as

many as 1 500 cans. How many flip-flops are required in the

counter

circuit to count all the items?
This is the easy one and again thanks for the support.

_________________________________________________________________
Get your FREE download of MSN Explorer at

Yes - what exactly is it that you need explained?
- What a flip-flop is?
- How a flip-flop works?
- Cascading flip-flops?
- How to interface the counter circuit to real-life?

Why do you need to count 1500 cans with a flip-flop type counter - there a
much neater and easier ways of doing it?

开云体育

Hi ,

I don't find anything wrong with the soln.. to
the problem... if you have any-other query then
can you be a bit specific and write the problem
in detail....

Regards

Himanshu Sharma

Still no one out there that can help me?
Please I really need some help here. If this is
the wrong group let
me know so that I can browse more for one that
can help me.

=====
Himanshu Sharma Ramdev

URL:

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--- In Electronics_101@y..., thecrack@t... wrote:

--- In Electronics_101@y..., adityan007@y... wrote:

the answer is 11
because 2 raise to 11 =2048
but 2 raised to 10=1024 which is less than 1500

Thankx

But can you please explain in more detail? You see I am new in this

world of

electronics and unfortunately I have to ask people like yourself to
get all the answers.
Another question:
How can a ring counter be converted to a Johnson counter?

Still no one out there that can help me?
Please I really need some help here. If this is the wrong group let
me know so that I can browse more for one that can help me.

Thank you

Jon

Thanks for the support:

Here is the question:
A counter is neede to count the number of cans passing on a

conveyor

belt. A pulse is generated each time a can passes a sensor,

which

in

turn triggers the counter circuit. The counter needed has to

count

as

many as 1 500 cans. How many flip-flops are required in the

counter

circuit to count all the items?
This is the easy one and again thanks for the support.

No offence...

I always thought that many people enjoyed
elecronics...

None taken. I love electronics. But to get started in understanding basic stuff and making first projects, I wouldn't recommend re-inventing the wheel. Start with simple stuff and then work your way up to...

trying to make a 2 bit processor outof
transistors just for the sake to learn

Which I have great respect for. I'm sure that by doing that you'll have an understanding that no kit would ever give.

I know that if I didn't start myself out with basic stuff like opamps, LED driver ICs, and 555 timers, I wouldn't have gotten the results I was looking for. It took me a while to learn how to make stuff properly.

You are right.. what it does is to compare the
voltage internally and then when the difference
is a particular voltage or a step of 3dB then it
flips another pin for an array of 10 pins in case
of 3914...that is whenever the voltage doubles...

Yeah. Parallel window comparators.

A comparator changes state (low/high...or zero volts/power supply voltage) when voltage is above/below a comparison voltage. When you put two comparators together, the voltages between their respective comparison voltages becomes a window. When the input is between the two, their output changes state.

A several window comparators in parallel (with sequential comparison voltages) essintially divide the input signal into steps when you look at the output. This is how the LED bargraph driver chip works. At any given voltage, the input will be within a given window. The particular LED fed by that window comparator will light up. As the voltage changes, it falls within different windows and will light up different LEDs.

I'm probably not explaining this very well.

Please read its data-sheet to gain more about the
proper working of it.... and just see that what
kind of refrence voltage you choose...

and



and



-Tavys

Hi,

I'm working with small trains, Z scale and realize that I'll need to
learn more than I know now (don't ask!) about the basics of dc.
Specifically how a dc transformer works and how it affects / is
affected by a load (the train).

I'm looking for something along the lines of an absolute primer, and
heavily illustrated if possible. The concepts seem to work better with
me if I can see them.

If anyone knows of a source for material like this, I'd really
appreciate hearing about it.

Thanks
John

There are a couple of different ways of going about it, depending on how
complex you want to get - the simplest way would involve using some kind of
temperature sensor (e.g. RTC thermistor), a comparator, and a transistor to
switch fan on and off (or a transistor/relay combination). You could get
more complex and implement fuzzy logic / PID control algorithms in a PIC and
use PWM to control the fan speed. Depends on how much time you have to play
...

Just a few idea's for you ...


J0n

I'm trying to controll the temperature/air circulation in a room
using a fan. The fan is rated 12VDC, 10A. What's the best way to
control the fans with a PIC or a low-power switch? A high-power
relay? Any help would be greatly appreciated.

It sounds to me like you are trying to build a color organ. This is a
device that divides a signal into frequency bands, say three, high,
medium and low frequencies. This is done by filtering. The output of
the filters are used to drive SCRs, the SCRs drive 110v lamps. Do you
have an oscope? If not you should get one. Hand held ones can go for
as little as $199. Or you can use a meter. The pin outs on the SCRs
are probably the problem. Are you using a fabricated PC board?

If you don't have an oscope and can't afford one, then you might want to
build one by either using a TV or LEDs. I have done both when I first
started out and found the projects to be both fun and educational.
Electronics is easier to understand if you can see what's happening.

Phil




*Message: 1
* Date: Sun, 19 Aug 2001 10:53:58 -0700
* From: markallen <markallen@...>
*Subject: light to sound kits

*I've been trying to make one of those sound to light kits that flash
*lights in time to music. I've tried three different kits, followed
*the instructions, and can't get them to work. I realize I'm kind of a
*moron, but I'm wondering if anyone knows any specific things that can
*go wrong. I've checked over the schematics, and everything looks like
*it's in the right place. Could I be damaging some of the components
*with static electricity?

hi

audio applications. It's
certainly possible to make one from scratch out
of transistors, but
when you can do it with an off the shelf part,
why not?

No offence...

I always thought that many people enjoyed
elecronics...

I am trying to make a 2 bit processor outof
transistors just for the sake to learn as this
has more fun than assembling kits...
I could have used the 128bit RISC processors...

Actually, what you describe sounds like an LED
bargraph circuit. The
LM3914 and LM3915 (national semiconductor)
chips are great for this.
They will light up an LED for each step
increase in voltage. Just
like you describe. These are the chips that
are always used for
level indicators, or LED type VU meters in

You are right.. what it does is to compare the
voltage internally and then when the difference
is a particular voltage or a step of 3dB then it
flips another pin for an array of 10 pins in case
of 3914...that is whenever the voltage doubles...


Please read its data-sheet to gain more about the
proper working of it.... and just see that what
kind of refrence voltage you choose...

if you want go for the 3916 as this has better
precision for the levels to change at 0.2bB...

Regards


=====
Himanshu Sharma Ramdev

URL:

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This was general.. lets be specific for each
frequency or say freq-range we have a particular
voltage assosiated so if you can make simple
transistor ckts that can trap up to a critical
voltage then you are through... With this i mean
that try to make simple transitor ckts that work
at a particular voltage say .1volt , .2volt and
so on as per the input range......this won't be
difficult and then you can attach the LEDs to
them to get the display....
Try and learn the basics rather than the Kits..

Actually, what you describe sounds like an LED bargraph circuit. The LM3914 and LM3915 (national semiconductor) chips are great for this. They will light up an LED for each step increase in voltage. Just like you describe. These are the chips that are always used for level indicators, or LED type VU meters in audio applications. It's certainly possible to make one from scratch out of transistors, but when you can do it with an off the shelf part, why not?

-Tavys

Hi ,

I am new to group.. but one suggestion i have to
make is why not we share what we know rather than
asking the questions.....:-)

Hope that all of us have something to share...

For your question what you can do is.. when-ever
there is a sound an electrical signal is
generated and now depending on the amplitude you
can light various LEDs display...

This was general.. lets be specific for each
frequency or say freq-range we have a particular
voltage assosiated so if you can make simple
transistor ckts that can trap up to a critical
voltage then you are through... With this i mean
that try to make simple transitor ckts that work
at a particular voltage say .1volt , .2volt and
so on as per the input range......this won't be
difficult and then you can attach the LEDs to
them to get the display....
Try and learn the basics rather than the Kits..

It helps more...

Regards

Himanshu sharma

I've been trying to make one of those sound to
light kits that flash
lights in time to music. I've tried three
different kits, followed
the instructions, and can't get them to work. I
realize I'm kind of a
moron, but I'm wondering if anyone knows any
specific things that can

=====
Himanshu Sharma Ramdev

URL:

__________________________________________________
Do You Yahoo!?
Make international calls for as low as $.04/minute with Yahoo! Messenger

I've been trying to make one of those sound to light kits that flash lights in time to music. I've tried three different kits, followed the instructions, and can't get them to work. I realize I'm kind of a moron, but I'm wondering if anyone knows any specific things that can go wrong. I've checked over the schematics, and everything looks like it's in the right place. Could I be damaging some of the components with static electricity?