Chip with simple program for Toy

Byron A Jeff wrote:

Any chance you could look at my thread "Circuit & Component Check" to
see if all looks well?

And you don't want 6V because then you'll have a problem regulating it. For
a 7805 you generally want at least 2.5V of headroom. So if you want regulated
5V then you'll want an input voltage of at least 7.5V. That's why I said 8V
in the original post.
Click to expand...
Would something like this work? (if I cut the end off and attach wires I
can plug into my breadboard!)

http://www.argos.co.uk/webapp/wcs/stores/servlet/ProductDisplay?storeId=10001&langId=-1&catalogId=2501&productId=111269

Or do I need something that says "DC" in it?

Thanks! :)

--
Danny
 
Danny T wrote:
<snip>

I don't understand the column headings given here:

http://www.rapidelectronics.co.uk/rkmain.asp?PAGEID=80010&CTL_CAT_CODE=30400&STK_PROD_CODE=M28648&XPAGENO=1

Anyone?

I need my PIC to drive 2x 3V motors... I've got two sets of motors - one
set are .45A, the other 1.07A (5240rpm and 13100rpm - I don't know which
will suit me best yet!)
 
Andrew Holme wrote:
<snip diagram>

Excellent. Thanks :)


When the battery is running low, and it's internal resistance is higher, the
motor will create more noise on the power supply rails. A low-dropout
regulator would better isolate the PIC from this than a simple dropper
diode; however, I'm 99% sure the diode will work - as long as your not
designing life support systems.
Click to expand...
Bummer! ;-)


The 1N4148 is only rated for a maximum forward current of 300mA. Use the
1N4001.
Click to expand...
For all 6 diodes? Those dropping the voltage, and the ones connected
back over the motors?

Thanks again :)

--
Danny
 
Andrew Holme wrote:

The 1N4148 is only rated for a maximum forward current of 300mA. Use the
1N4001.
Click to expand...
That's 1A, correct?

One set of my motors (much higher RPM than the other) have a max current
of 1.07A... If I need to use them, am I still ok with these? What about
if I use a lower voltage than the max? Or should I find something rated
higher just to be safe?

(It's not a life support system ;))

If I destroy up (a diode, resistor, MOSFET etc.), is it easy to detect?
Will they stop conducting, or could they potentially blow other things
along the way (eg. if a resistor stopped resisting!!!)
--
Danny
 
Final question....

http://www.rapidelectronics.co.uk/rkmain.asp?PAGEID=80010

Would that allow me to test without using batteries? It does 6V, which
is about the same as 4AA batteries. I don't entirely understand the
current though - does 3A mean it can produce 3A without blowing a fuse,
but it'll run small things fine, or will this just fry things that don't
need such a high current?

Thanks,

Danny
 
On Fri, 31 Dec 2004 17:29:24 -0000, "Andrew Holme" <andrew@nospam.com>
wrote:

Didoes drop voltage not current. Silicon diodes (e.g. 1N4148 or 1N4001)
drop about 0.7V so one would probably be adequate; but two, in series, would
be safer.
Click to expand...
Um, yeah, but they drop voltage _according_ to current! If they're
dropping 0,7V., they're not passing much current! Diodes are a crap
way to drop voltage unless the load is light and predictable!!!

miles
 
Danny T wrote:
Final question....

http://www.rapidelectronics.co.uk/rkmain.asp?PAGEID=80010

Would that allow me to test without using batteries? It does 6V, which
is about the same as 4AA batteries. I don't entirely understand the
current though - does 3A mean it can produce 3A without blowing a
fuse, but it'll run small things fine, or will this just fry things
that don't need such a high current?
Click to expand...
That link doesn't work for me but I assume it's some sort of mains power
supply.

You need a REGULATED 6.0V supply. A wallwart may *not* be suitable
(excessive ripple, peak > 6V).

Yes, it means you can draw anything from zero up to a maximum of 3A.

Power supplies can regulate the voltage or the current - but not both at
once.
 
Danny T wrote:
Final question....

http://www.rapidelectronics.co.uk/rkmain.asp?PAGEID=80010

Would that allow me to test without using batteries? It does 6V, which
is about the same as 4AA batteries. I don't entirely understand the
current though - does 3A mean it can produce 3A without blowing a
fuse, but it'll run small things fine, or will this just fry things
that don't need such a high current?

Thanks,

Danny
Click to expand...
If you mean order code 85-1820 then, yes, that would be fine.
 
Andrew Holme wrote:
That link doesn't work for me but I assume it's some sort of mains power
supply.
Click to expand...
Nor me!


You need a REGULATED 6.0V supply. A wallwart may *not* be suitable
(excessive ripple, peak > 6V).
Click to expand...
Yep, guessed this. I had to buy an unregulated 300mA supply for my pic
programmer (why, I don't know!), but this one has regulation figures, so
I assume it is. It is the one you found (85-1820), but before I order my
stuff, I'd like to ask you to check "Miles Harris" reply in my
"Calculating resistors required" thread :-\

Ta,

Danny
 
John Popelish wrote:

5. You should also have a capacitor between each motor driver fet
source and the positive end of its motor, to act as a small local
supply, so those high frequency on-off edges don't get back to the
battery and then into the PIC.
A .1 uf film or ceramic in parallel with a few hundred microfarad
electrolytic might be enough. A 1 uf film or ceramic in parallel with
a 1000 uf electrolytic would be better.
Click to expand...
Which leg of the MOSFET should it connect to? Not sure I understand its
purpose :-\

--
Danny
 
You might try to start with

http://www.ScienceOxygen.com/idea.html

It does not give you step-by-step instruction; it is just a
collection of links about science ideas. Probably you can
have some new ideas from that...
 
In article <41d7d47a$0$34063$ed2e19e4@ptn-nntp-reader04.plus.net>,
Danny T <danny@nospam.oops> wrote:
-Byron A Jeff wrote:
-
-Any chance you could look at my thread "Circuit & Component Check" to
-see if all looks well?

I'll go and take a look.

-
-> And you don't want 6V because then you'll have a problem regulating it. For
-> a 7805 you generally want at least 2.5V of headroom. So if you want regulated
-> 5V then you'll want an input voltage of at least 7.5V. That's why I said 8V
-> in the original post.
-
-Would something like this work? (if I cut the end off and attach wires I
-can plug into my breadboard!)
-
-http://www.argos.co.uk/webapp/wcs/stores/servlet/ProductDisplay?storeId=10001&langId=-1&catalogId=2501&productId=111269
-
-Or do I need something that says "DC" in it?

It would but it's extremely expensive. Almost everyone has old equipment
(phones, toys, small electronics) that are powered by wall warts. I have
a junk box full of them.

BAJ
 
On 01 Jan 2005 17:04:46 GMT, Ricky Romaya <something@somewhere.com>
wrote:

I want to design and build a very simple audio amplifier to drive my
8ohms speakers from (onboard) pc soundcard.
Click to expand...
in french; use Babelfish to translate ..
http://f5jtz.club.fr/pjacquet/bf15.htm

Happy New Year!
--
Regards & Happy Holidays Everyone, SPAJKY ÂŽ
& visit my site @ http://www.spajky.vze.com
"Tualatin OC-ed / BX-Slot1 / inaudible setup!"
E-mail AntiSpam: remove ##
 
Hmm,
We've know about "fish caps" for some time. They get a bad rap for
failure in camcorders after some years. Usually the ones I've seen are
surface mount cans and the camcorders smell like fish. Here's a search
link in the repair section:

http://groups-beta.google.com/group/sci.electronics.repair/search?group=sci.electronics.repair&q=fish+caps&qt_g=1&searchnow=Search+this+group
Richard
 
Amazing - they actually use a derivative of fish oil in these
capacitors! Now that explains the awful smell.
 
I happened to blow up a red sanyo os-con at home by accident this time.
I had put it in backwards. There was a muffled 'pop' and green smoke
was coming out of the case through the ventilation holes :) Oh my god
you can't describe how bad the acrid smell is.
 
Rich Grise wrote:

I vote for the TBA820M 'cause it's the coolest. :)
Click to expand...
Especially if you glue a piece of aluminum on top of it. ;-)

--
John Popelish
 
John Popelish wrote:

If the mosfets drove resistors instead of something inductive, there
would still be the power supply bounce, but no extra voltage spike on
the drain at turn off.
Click to expand...
Right, got that. Thanks! :eek:)

--
Danny
 
Byron A Jeff wrote:

It would but it's extremely expensive. Almost everyone has old equipment
(phones, toys, small electronics) that are powered by wall warts. I have
a junk box full of them.
Click to expand...
I've ordered the item with order code 85-1820 from www.rapidelec.co.uk.
It's still expensive compared to the others I have lying around, but
it's 3A, and these are all x00mA! I doubt I'll need that, but it's
better to have it than not!

Thanks :)
--
Danny
 
3. The speaker ties to the same "ground" as the main +5V supply, but
it seems to have its own +9V supply. Surely each should return to
it's own power source?!

The grounds are connected; note the earth symbols:

|
|
-------
-----
---
-
Click to expand...

Actually, maybe you can explain the way that NPN 2N3904 transistor
is connected? It looks odd to me that the emitter is not tied to
ground, but the collector is. I am not sure I see what it is
supposed to do in this circuit.

Dominic
 
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