Hello Group ,

I build scale r/c boats and I want to build my own 12 motor speed
controller to hook up to my receiver which requires a 3 wire hook up
at the receiver , wire colors = red,black,white .
I want to make an electronic speed controller with variable forward &
reverse speeds .
I have been looking for a plan to make a 12 volt speed controller but
to date I have only found a plan for a 6 volt controller ?

Can anyone help with this problem ?

Thank you for your help and time ,
Darle Bennett
dwb4926@...

Hello,

I'm new to the group and am currently working on building an analog
synthesizer. I have some good circuit designs and decent plans for
execution. My next step is PCB design. I have been using eagle for
windows and was wondering if anything better exists for doing schemes
and PCB layout.

Thanks,

Ethan

I need help again, I have a Hewlett Packard 722 C printer and
there is a diode molded into the cord that goes from the power
supply to the printer. The diode is bad and can't be replaced
because it is molded into the cord. I would like to fix this
problem myself because a new power supply costs $52.00 and that is
a lot of money when a fifty cent diode is the only problem.

Does anybody know the purpose for the diode ('s) and can I run the
printer by without the diode ('s). I can't tell much about the
diodes because the rubber is melted.

Thanks

Jim

A half-mile isn't much, but being the fascist organization that it is, the FCC won't allow it. Without applying for a license I believe you're limited to 100 mW, which is about good to the end of your driveway.

From: Himanshu Sharma <hs_ramdev@...>
Reply-To: Electronics_101@...
To: Electronics_101@...
Subject: Re: [Electronics_101] Wireless A/V
Date: Wed, 29 Aug 2001 07:10:24 -0700 (PDT)

Hi ,

Before you think what frequencies to use for the
A/V connection try to get the list of what
frequencies are available for free...

In any case a VHF would do fine and if you have a
lot of connections or very high density network
then go for UHF band...

Regards

Himanshu sharma

--- sjohns10@... wrote:

Hi. I have a project that is going to use
wireless audio/video. Does
anyone know what frequency is the best (range,
picture and sound
quality) for A/V transmission? I know there's
2.4GHz, around 900 MHz,
and ones that transmit right to your television
(usually channel 19
or 59). I'd like to keep the price low (under
US$300). It doesn't
need to transmit or recieve more than half-mile
away. It is mostly
flat ground with some trees in the area.
Thanks.

sjohns10

=====
Himanshu Sharma Ramdev

URL:

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

_________________________________________________________________
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Thank you. This was the help I was looking for.

This is how my power supply circuit looks so far...

A 25V/2A transformer is rectified through four 1N5404s and then passes over a 2200uF/35V cap. These two rails (pos and common) then feed two subcircuits. One is a LM317 which varies the output through a pot. I'm guessing I can get about 0-25V from this. And the other is a 7805T to get the constant +5V output. (There are small caps at each output to control ripple.)

I'm also thinking of adding another subcircuit - a 7812T for a fixed +12V output.

I doubt that I would be using all three outputs at the same time. Mostly it will be for doing breadboard work.

Whadya think?

-Mike

From: "Jonathan Luthje" <jluthje@...>
Reply-To: Electronics_101@...
To: <Electronics_101@...>
Subject: Re: [Electronics_101] Re: Capacitors in power supply circuits
Date: Wed, 29 Aug 2001 09:43:16 +1000

Mike,

There are advantages and disadvantages of both approaches, out of
personal preference and a costing perspective, based on your circuit
description, I would use one large cap (i.e. around 6600uF) for both
circuits.

Depending on your regulation methods though, I would suggest that you think
about your PSU - generally the more voltage you are dropping off your
supply, the more heat you generate and the higher rated your components need
to be. If I were building a supply with +5 and a variable 0-30 (for example)
supply, then you would need a 35V rated transformer, which means you need to
drop 30V off your main supply rail to achieve a +5V rail (with a 7805 reg or
similar), which means that you are going to be dissapating a LOT of heat
Just a few thoughts for the day ...


Regards,


Jon

Maybe I misspoke in my posting...I wasn't asking whether or not to
use a large cap, but whether I needed two of them (one for each
subcircuit).

I have positive and ground rails and planned on having a single
2200uF cap across them to remove ripple from the mains. These lines
would then feed the two subcircuits (one for a variable supply and
one for a +5V supply).

My question is...Do I need a large cap at the input to each
subcircuit or will a single one at the positive/ground rails suffice?

-Mike


--- In Electronics_101@y..., "Jonathan Luthje" <jluthje@p...> wrote:

dear dot-dot

no it is not neccessary to run a capacitor on each of your "sub

circuits",

in fact, if you take it to the other extreme, you don't really need

to run a

capacitor at all! The supply will still work - although you may end

up with

quite a bit of noise on the line ... say around 60Hz?

The primary purpose of having a large-ish cap on the supply is to

remove the

ripple from the mains and to provide any surge currents that you or

your

project may require, rather than trashing your transformer /

rectifier

arrangement (yes, everyone I realise that there are other

advantages of

having capacitors on the supply line .. but for a basic power

supply, there

is no need to go into them). Smoothing is very handy when you are

working

with low voltage logic / mcu's / audio. Having a high surge

capability is

good when working with servo's, other capacitative loads, audio,
amplification etc.

Basically the bigger the better, personally I would go the whole

hog and

spend the few extra dollars on a bigger cap, or bigger set of caps

(if you

are suppling +/- rails you will probably need two anyway).

Regards,

J0n (aka dot-dash-dash-dash dash-dash-dash dash-dot)





----- Original Message -----
From: ". ." <dnixon9@h...>
To: <Electronics_101@y...>
Sent: Tuesday, August 28, 2001 1:45 PM
Subject: [Electronics_101] Capacitors in power supply circuits

I'm new to electonics and one of my first projects is a benchtop

power

supply. It's going to have variable and +5V outputs.

I've seen many circuit designs for multiple-output power supplies

and

nearly

all of them have a large (1000 or 2200 uF) cap at EACH of the

subcircuits.

Is this necessary?

If I'm using a single transformer for both subcircuits why can't

I have a

single 2200 uF cap after the bridge rectifier that feeds each of

the

subcircuits?



_________________________________________________________________
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Electronics_101-unsubscribe@y...



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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????

The only reason for the closed loop mode was the
band-width that you get(increased...)and the
impedence...

If you wish you can choose the non-inverting mode
or many other configurations depending upon the
input impednece requirments.... even use a buffer
if you want no effects on the input wave....

Regards

Himanshu sharma

=====
Himanshu Sharma Ramdev

URL:

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

Hi ,

Before you think what frequencies to use for the
A/V connection try to get the list of what
frequencies are available for free...

In any case a VHF would do fine and if you have a
lot of connections or very high density network
then go for UHF band...

Regards

Himanshu sharma

--- sjohns10@... wrote:

Hi. I have a project that is going to use
wireless audio/video. Does
anyone know what frequency is the best (range,
picture and sound
quality) for A/V transmission? I know there's
2.4GHz, around 900 MHz,
and ones that transmit right to your television
(usually channel 19
or 59). I'd like to keep the price low (under
US$300). It doesn't
need to transmit or recieve more than half-mile
away. It is mostly
flat ground with some trees in the area.
Thanks.

sjohns10

=====
Himanshu Sharma Ramdev

URL:

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

开云体育

Mike,

There are advantages and disadvantages of both approaches, out of
personal preference and a costing perspective, based on your circuit
description, I would use one large cap (i.e. around 6600uF) for both
circuits.

Depending on your regulation methods though, I would suggest that you think
about your PSU - generally the more voltage you are dropping off your
supply, the more heat you generate and the higher rated your components need
to be. If I were building a supply with +5 and a variable 0-30 (for example)
supply, then you would need a 35V rated transformer, which means you need to
drop 30V off your main supply rail to achieve a +5V rail (with a 7805 reg or
similar), which means that you are going to be dissapating a LOT of heat
Just a few thoughts for the day ...


Regards,


Jon

I'd go for one each, they're not exactly expensive, unless you're going for
6800uF at 63V or upwards...

chirsc

Maybe I misspoke in my posting...I wasn't asking whether or not to
use a large cap, but whether I needed two of them (one for each
subcircuit).

I have positive and ground rails and planned on having a single
2200uF cap across them to remove ripple from the mains. These lines
would then feed the two subcircuits (one for a variable supply and
one for a +5V supply).

My question is...Do I need a large cap at the input to each
subcircuit or will a single one at the positive/ground rails suffice?

-Mike


--- In Electronics_101@y..., "Jonathan Luthje" <jluthje@p...> wrote:

dear dot-dot

no it is not neccessary to run a capacitor on each of your "sub

circuits",

in fact, if you take it to the other extreme, you don't really need

to run a

capacitor at all! The supply will still work - although you may end

up with

quite a bit of noise on the line ... say around 60Hz?

The primary purpose of having a large-ish cap on the supply is to

remove the

ripple from the mains and to provide any surge currents that you or

your

project may require, rather than trashing your transformer /

rectifier

arrangement (yes, everyone I realise that there are other

advantages of

having capacitors on the supply line .. but for a basic power

supply, there

is no need to go into them). Smoothing is very handy when you are

working

with low voltage logic / mcu's / audio. Having a high surge

capability is

good when working with servo's, other capacitative loads, audio,
amplification etc.

Basically the bigger the better, personally I would go the whole

hog and

spend the few extra dollars on a bigger cap, or bigger set of caps

(if you

are suppling +/- rails you will probably need two anyway).

Regards,

J0n (aka dot-dash-dash-dash dash-dash-dash dash-dot)





----- Original Message -----
From: ". ." <dnixon9@h...>
To: <Electronics_101@y...>
Sent: Tuesday, August 28, 2001 1:45 PM
Subject: [Electronics_101] Capacitors in power supply circuits

I'm new to electonics and one of my first projects is a benchtop

power

supply. It's going to have variable and +5V outputs.

I've seen many circuit designs for multiple-output power supplies

and

nearly

all of them have a large (1000 or 2200 uF) cap at EACH of the

subcircuits.

Is this necessary?

If I'm using a single transformer for both subcircuits why can't

I have a

single 2200 uF cap after the bridge rectifier that feeds each of

the

subcircuits?



_________________________________________________________________
Get your FREE download of MSN Explorer at

To unsubscribe from this group, send an email to:
Electronics_101-unsubscribe@y...



Your use of Yahoo! Groups is subject to

It won't kill it if you put a resistor in series with it to take up the slack. But the resistor should be chosen so that its power rating is high enough and so that it limits the current through the LED to within the specs of the LED.


<html></html>

From: "Jayson" <woodrufj@...>
Reply-To: Electronics_101@...
To: Electronics_101@...
Subject: [Electronics_101] Another LED Q
Date: Mon, 27 Aug 2001 21:33:13 -0000

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

_________________________________________________________________
Get your FREE download of MSN Explorer at

:

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?

What will your fan and other things be powered by? For example, are they powered by AC or DC? If they are powered by AC, you will need to provide rectification for the diode. If the fan and other things are powered by DC, you could connect the diode directly across the source (fan side of the switch of course), and don't forget the current limiting resistor.


_________________________________________________________________
Get your FREE download of MSN Explorer at

dear dot-dot

no it is not neccessary to run a capacitor on each of your "sub circuits",
in fact, if you take it to the other extreme, you don't really need to run a
capacitor at all! The supply will still work - although you may end up with
quite a bit of noise on the line ... say around 60Hz?

The primary purpose of having a large-ish cap on the supply is to remove the
ripple from the mains and to provide any surge currents that you or your
project may require, rather than trashing your transformer / rectifier
arrangement (yes, everyone I realise that there are other advantages of
having capacitors on the supply line .. but for a basic power supply, there
is no need to go into them). Smoothing is very handy when you are working
with low voltage logic / mcu's / audio. Having a high surge capability is
good when working with servo's, other capacitative loads, audio,
amplification etc.

Basically the bigger the better, personally I would go the whole hog and
spend the few extra dollars on a bigger cap, or bigger set of caps (if you
are suppling +/- rails you will probably need two anyway).

Regards,

J0n (aka dot-dash-dash-dash dash-dash-dash dash-dot)

I'm new to electonics and one of my first projects is a benchtop power supply. It's going to have variable and +5V outputs.

I've seen many circuit designs for multiple-output power supplies and nearly all of them have a large (1000 or 2200 uF) cap at EACH of the subcircuits. Is this necessary?

If I'm using a single transformer for both subcircuits why can't I have a single 2200 uF cap after the bridge rectifier that feeds each of the subcircuits?



_________________________________________________________________
Get your FREE download of MSN Explorer at

I forgot to explain that. I have no orange in my rear lights.The red
obviously lights up when the light are on, but then the red gets
brighter when the brakes or blinker is applied.

And I was having a brain fart when I asked the LED on indicator
question, I figured it out right after I hit send.

Thanks for the diagram, It'll be a great starting point.

Jay W


--- In Electronics_101@y..., "Jonathan Luthje" <jluthje@p...> wrote:

Just a query of my own: Why do you want your blinkers on "dim" when

your

tail-lights are on?

It is unlikely that 2.4V would destroy a 2.1Vf LED ... it may reduce

it's

life slightly, but intermittent triggering at 14% past it's rated

capacity

shouldn't do any severe damage.

As far as using a high current to trigger a led - just put the LED

with a

series dropping resistor in parallel with your load - when the load

goes on,

so does the LED. I have quite a few of this configuration in the

'Cruiser

.... works like a charm!


Hope this has helped - if you have any more q's ... post away!


Regards,


J0n

Hi. I have a project that is going to use wireless audio/video. Does
anyone know what frequency is the best (range, picture and sound
quality) for A/V transmission? I know there's 2.4GHz, around 900 MHz,
and ones that transmit right to your television (usually channel 19
or 59). I'd like to keep the price low (under US$300). It doesn't
need to transmit or recieve more than half-mile away. It is mostly
flat ground with some trees in the area. Thanks.

sjohns10

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.

probably due to them being very bright leds. i dunno. find similar leds and price them out?


--

/|
|&#92;
|/|
/ |
| /
|/

G'day Jason,
Just a few thoughts on your LED lighting queries:

Assuming that you are ok with the rest of the wiring details (i.e. actually
getting the LED's into the correct positions, parallel & series wiring
etc.), I would suggest that for ease of installation, you use multiple sets
of ultra-bright 5mm LED's (amber) for your marker lights, and obviously red
for the brake/tail lights. For your bright / dim, I would just use a diode
and a resistor in series with your LED's and another diode directly
connected to your LED series. The resistor provides the current limiting to
dim the led's, while the two diodes protect the rest of your electricals
from potential feedback (i.e. if you applied the brake, then your tail
lights would light up, and the rest of your dash lights ... that is, before
the resistor went into meltdown from too much current).

I have attached a suggested circuit diagram to explain my rambling ...

As far as your blinker relay goes, perhaps replacing it with another would
be the simplest alternative - I have an electronic unit on my Mazda which
locks on solid (i.e. doesn't blink at all) if it doesn't push through enough
current - conversely my 1979 LandCruiser doesn't care how many bulbs are
blown - it will blink regardless - simply because it has a cheaper flasher
relay in it without the current sensing. For $1 ... you can't beat it for
simplicity! :)

Just a query of my own: Why do you want your blinkers on "dim" when your
tail-lights are on?

It is unlikely that 2.4V would destroy a 2.1Vf LED ... it may reduce it's
life slightly, but intermittent triggering at 14% past it's rated capacity
shouldn't do any severe damage.

As far as using a high current to trigger a led - just put the LED with a
series dropping resistor in parallel with your load - when the load goes on,
so does the LED. I have quite a few of this configuration in the 'Cruiser
.... works like a charm!


Hope this has helped - if you have any more q's ... post away!


Regards,


J0n

--- In Electronics_101@y..., "Jayson" <woodrufj@y...> wrote:

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?

I'd think you could just use a DPST (Double Pole Single Throw)
switch. It's like a regular switch, but with four connections instead
of two(SPST). SPST switches only control one circuit, while DPST
switches are like two SPSTs linked together so you can control two
seperate circuits at the same time. Just get a DPST switch that can
handle the current of your application and wire one side of it to the
fan and power source and the other side to the LED and its own power
source. I hope this makes sense.

sjohns10