Fustrated Beginner

Archiver · 2000-10-18 18:05

Hello All, While I'm sending this message, I am searching through the
archives for an answer that is probably obvious to most of you. I am
fairly new to electronics and stamping. Here is the question All I
am trying to do is drive a relay with my BSII. I've tried many ways but all
have failed. Currently, I must not very good with shematics b/c I have
looked at some but it still does not work. The relay is a simple SPDT rely I
picked up from RadioShack that turns on/off at 5V. I tried using two
stamp pins, one low and one high. I tried using a NPN and a PNP transistor
connected to a stamp pin but nothing seems to turn that coil on. If I take a
6v battery and connect it directly to the coil, it works. By the way most of
my transistors seem to blow up. Can anyone give help in laymens terms as
to how to go about connecting the wires. Right now I'm using the BSII with
it's carrier board from the kit and and an addit!
ional breadboard. Sorry for such a simple question. Any help is
greatly appreciated. :-)

Visit http://www.ChurchItinerary.com today!!

Archiver · 2000-10-18 18:44

Read http://www.al-williams.com/wd5gnr/stampfaq.htm#s2.5

and http://www.al-williams.com/wd5gnr/stampfaq.htm#s2.29

The idea is to connect the base of a 2N2222 (or similar) transistor to the
Stamp via a resistor (say 1K or so). The emitter goes to ground and the
collector goes to one end of the relay coil. The other end goes to +V.
Here's the tricky part. Take a diode (1N914, 1N4148, even an 1N4001) and put
the banded end to the +V end of the coil and the non-banded end to the other
end of the coil (the collector end).

When you set the Stamp pin high, the transistor will go into saturation. The
Vce will be about .2V or so and the relay should snap on. When the pin goes
low, the transistor falls out of saturation, Vce climbs to about 5V and the
coil is off. Without the diode, the switching time of the transistor can
create a huge voltage in the coil (inductors generate voltage in proportion
to time variations in voltage -- that's why they resist AC but not DC).
That's what is blowing your transistor.

You can also use a MOSFET, but the old transistor circuit is a well-known
design.

Regards,

Al Williams
AWC
*Expand your Stamp I/O: http://www.al-williams.com/awce/pak3.htm

>

Original Message

> From: ContactMe@S... [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=vQflInjM8XjKJO4cRPV07C85e2IjL4Y4Ruh7dBtAyhspVr8VHdfbrmHrAeAk3i7Nh3Yw3p06oTAvppaNqPbIdL7Bw18]ContactMe@S...[/url
> Sent: Wednesday, October 18, 2000 12:05 PM
> To: basicstamps@egroups.com
> Subject: [noparse][[/noparse]basicstamps] Fustrated Beginner
>
>
>
> Hello All, While I'm sending this message, I am searching
> through the archives for an answer that is probably obvious to
> most of you. I am fairly new to electronics and
> stamping. Here is the question All I am trying to
> do is drive a relay with my BSII. I've tried many ways but all
> have failed. Currently, I must not very good with
> shematics b/c I have looked at some but it still does not work.
> The relay is a simple SPDT rely I picked up from RadioShack
> that turns on/off at 5V. I tried using two stamp pins, one
> low and one high. I tried using a NPN and a PNP transistor
> connected to a stamp pin but nothing seems to turn that coil
> on. If I take a 6v battery and connect it directly to the coil,
> it works. By the way most of my transistors seem to blow
> up. Can anyone give help in laymens terms as to how to go
> about connecting the wires. Right now I'm using the BSII with
> it's carrier board from the kit and and an addit!
> ional breadboard. Sorry for such a simple question. Any
> help is greatly appreciated. :-) 
>

>

>
> Visit http://www.ChurchItinerary.com today!!
>
>

Archiver · 2000-10-18 19:03

Here's a schematic for connecting relays & drive
transistors to the Basic Stamp.
http://www.rentron.com/pc-relay.htm

As Al Williams stated in his reply, without the flyback
diode to protect the drive transistor, that nasty spike
will blow up your transistors when you de-energize
the relay coil.

The schematic on the above page should help.

Regards,

Bruce Reynolds
webmaster@r...
http://www.rentron.com

Original Message

From: <ContactMe@S...>
To: <basicstamps@egroups.com>
Sent: Wednesday, October 18, 2000 11:05 AM
Subject: [noparse][[/noparse]basicstamps] Fustrated Beginner

|
| Hello All, While I'm sending this message, I am searching through the
archives for an answer that is probably obvious to most of you. I am
fairly
new to electronics and stamping. Here is the question All I am
trying
to do is drive a relay with my BSII. I've tried many ways but all have
failed. Currently, I must not very good with shematics b/c I have looked
at
some but it still does not work. The relay is a simple SPDT rely I picked up
from
RadioShack that turns on/off at 5V. I tried using two stamp pins, one low
and one
high. I tried using a NPN and a PNP transistor connected to a stamp pin but
nothing seems to turn that coil on. If I take a 6v battery and connect it
directly to the coil, it works. By the way most of my transistors seem to
blow
up. Can anyone give help in laymens terms as to how to go about
connecting the
wires. Right now I'm using the BSII with it's carrier board from the kit and
and
an addit!
| ional breadboard. Sorry for such a simple question. Any help is
greatly
appreciated. :-) 
|

|
| Visit http://www.ChurchItinerary.com today!!
|
|
|
|

Archiver · 2000-10-18 20:37

The best way is to use a ULN2803A, driving directly load or trough relay

Datasheet should be available on the net or I think others on group will
answer about this

Archiver · 2000-10-19 12:40

Original Message

From: <ContactMe@S...>
To: <basicstamps@egroups.com>
Sent: Wednesday, October 18, 2000 1:05 PM
Subject: [noparse][[/noparse]basicstamps] Fustrated Beginner

>
> Hello All, While I'm sending this message, I am searching through
the archives for an answer that is probably obvious to most of
you. I am fairly new to electronics and stamping. Here is the
question All I am trying to do is drive a relay with my BSII. I've
tried many ways but all have failed. Currently, I must not very good
with shematics b/c I have looked at some but it still does not work.
The relay is a simple SPDT rely I picked up from RadioShack that turns
on/off at 5V. I tried using two stamp pins, one low and one high. I
tried using a NPN and a PNP transistor connected to a stamp pin but
nothing seems to turn that coil on. If I take a 6v battery and connect
it directly to the coil, it works. By the way most of my transistors
seem to blow up. Can anyone give help in laymens terms as to how to
go about connecting the wires. Right now I'm using the BSII with it's
carrier board from the kit and and an addit!
> ional breadboard. Sorry for such a simple question. Any help is
greatly appreciated. :-) 
>

-
>
> Visit http://www.ChurchItinerary.com today!!
>
> YOU NEED TO TAKE THE SIGNAL FROM THE STAMP TO A DARLINGTON SWITCHING
TRANSISTOR. SEE SCOTT EDWARDS ARTICLE IN NUTS N VOLTS 'STAMP APPLICATION NO.
6'
THIS WORKS REALLY WELL.
KEITH MOORE.
>
>

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Fustrated Beginner

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