Using Transistor
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Hi! Having a slight problem with a 2N2222 transistor.
I have wired a circuit like the one shown in N&V, Vol. 1, Article 6.
It has an inline 390 Ohm resistor from P7 to base of 2N2222. The
load side goes to a SPST relay on the +12V side. And, the other pin
goes to ground.
I have used the same diode, N4002, with the band to the +12V side.
My circuit is keeping the relay always active even when I put a low
on pin 7 which is the pin used in the article.
If I tie the base to GND, then the relay isn't active. It does seem
to quiver a bit, but doesn't go active.
Differences in my circuit:
Using 330 Ohm resistor. (RS didn't have 390)
Is there a polarity to the coil in the relay? I didn't see any on
the packaging or in the schematic in the article.
Thanks,
Frank
I have wired a circuit like the one shown in N&V, Vol. 1, Article 6.
It has an inline 390 Ohm resistor from P7 to base of 2N2222. The
load side goes to a SPST relay on the +12V side. And, the other pin
goes to ground.
I have used the same diode, N4002, with the band to the +12V side.
My circuit is keeping the relay always active even when I put a low
on pin 7 which is the pin used in the article.
If I tie the base to GND, then the relay isn't active. It does seem
to quiver a bit, but doesn't go active.
Differences in my circuit:
Using 330 Ohm resistor. (RS didn't have 390)
Is there a polarity to the coil in the relay? I didn't see any on
the packaging or in the schematic in the article.
Thanks,
Frank
Comments
the transistor to conduct and energize the relay. Some relays have a built
in diode and polarity is important. You may not be able to tell using a
multimeter as the coil resistance may be too low to tell if any polarity is
there. Best to check the data sheet on the relay if possible. I am
assuming from your description the circuit is wired stamp pin to resistor,
other end of resistor to base of transistor. Emitter of transistor to
ground, collector of transistor to relay coil, other end of relay coil to
+12 volts.
jim
http://www.geocities.com/jimforkin2003/
Original Message
From: franksmith512 [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=CpwiselsAAYi1rRe91XK_tA1fMcD56NFl5Slwl92MmBT5D3_xP0-ejU4dLupIgZ1Y6vTVwRNHVtO_FJIv4Q-_w]franksmith512@y...[/url
Sent: Saturday, December 20, 2003 5:15 PM
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] Using Transistor
Hi! Having a slight problem with a 2N2222 transistor.
I have wired a circuit like the one shown in N&V, Vol. 1, Article 6.
It has an inline 390 Ohm resistor from P7 to base of 2N2222. The
load side goes to a SPST relay on the +12V side. And, the other pin
goes to ground.
I have used the same diode, N4002, with the band to the +12V side.
My circuit is keeping the relay always active even when I put a low
on pin 7 which is the pin used in the article.
If I tie the base to GND, then the relay isn't active. It does seem
to quiver a bit, but doesn't go active.
Differences in my circuit:
Using 330 Ohm resistor. (RS didn't have 390)
Is there a polarity to the coil in the relay? I didn't see any on
the packaging or in the schematic in the article.
Thanks,
Frank
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to collector of transistor.
Check out my web site for schematics.
jim
http://www.geocities.com/jimforkin2003/
Original Message
From: franksmith512 [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=6Um1c-kBbuDX5W-XP8u9j_dfdwM0P_xTxYoLyGQVQIe6d6KWchitzYLr_EUR1fPERgpOUTLFOzp6-6rDQqhx6cU]franksmith512@y...[/url
Sent: Saturday, December 20, 2003 5:15 PM
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] Using Transistor
Hi! Having a slight problem with a 2N2222 transistor.
I have wired a circuit like the one shown in N&V, Vol. 1, Article 6.
It has an inline 390 Ohm resistor from P7 to base of 2N2222. The
load side goes to a SPST relay on the +12V side. And, the other pin
goes to ground.
I have used the same diode, N4002, with the band to the +12V side.
My circuit is keeping the relay always active even when I put a low
on pin 7 which is the pin used in the article.
If I tie the base to GND, then the relay isn't active. It does seem
to quiver a bit, but doesn't go active.
Differences in my circuit:
Using 330 Ohm resistor. (RS didn't have 390)
Is there a polarity to the coil in the relay? I didn't see any on
the packaging or in the schematic in the article.
Thanks,
Frank
To UNSUBSCRIBE, just send mail to:
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from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
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