Transistor selection
Hi Group,
I am making a motor controller with a BS2 and bought a couple of transistors
from the local NTE dealer. I was hoping someone could give a once over on the
datasheet and let me know if this is suitable to work with the basic stamp.
My motor is 120vdc with .80amps and I plan on using PWM with it.
<A HREF="mailto:basicstamps@egroups.com">http://www.nteinc.com/specs/2300to239
9/NTE2318.html</A>
http://www.nteinc.com/specs/2300to2399/NTE2313.html
Any comments would be appreciated.
I am making a motor controller with a BS2 and bought a couple of transistors
from the local NTE dealer. I was hoping someone could give a once over on the
datasheet and let me know if this is suitable to work with the basic stamp.
My motor is 120vdc with .80amps and I plan on using PWM with it.
<A HREF="mailto:basicstamps@egroups.com">http://www.nteinc.com/specs/2300to239
9/NTE2318.html</A>
http://www.nteinc.com/specs/2300to2399/NTE2313.html
Any comments would be appreciated.
Comments
http://www.nteinc.com/specs/2300to2399/NTE2313.html
and
http://www.nteinc.com/specs/2300to2399/NTE2318.html
and require lots of base drive. The 2313 would need ~200 ma, and the 2318
needs ~350 ma. In either case, you need a driver stage between the
transistors and the stamp, since the stamp should be used at ~10 ma per pin.
Consider lower voltage transistors, like 300 volt units, because you always
pay a performance price for higher voltage transistors. You could afford
darlington transistors with their higher saturation voltage since you are
operating a 120 Volt system, but remember that the darlingtons are slow to
turn off when using PWM.
Consider MOSFETS, but again, do not use higher voltage units than necessary,
because you pay a price in on-resistance, (and therefore, power loss). I
have not used MOSFETS in several years, so cannot recommend a part number
offhand. If the PWM frequency can be kept low, it might be possible to find
a logic-level device that could be directly driven from the stamp. (You need
higher drive voltage & current for fast switching).
Perhaps the best approach would be to search for a ready-to-go H bridge,
especially if you can find a MOSFET motor driver, where they have
incorporated necessary spike protection. Someone on this list may be able
to recommend one. You have an application that can make lots of smoke if
not done correctly.
Ray McArthur
Original Message
From: <electronguy@a...>
To: <basicstamps@egroups.com>
Sent: Friday, April 21, 2000 6:53 PM
Subject: Re: [noparse][[/noparse]basicstamps] Transistor selection
> those address's should have come out
>
> http://www.nteinc.com/specs/2300to2399/NTE2313.html
>
> and
>
> http://www.nteinc.com/specs/2300to2399/NTE2318.html
I wish to use am bs2sx to drive two 12 volt stepper motors. I can do this
with a uln2003 or uln2803 darlinton transistor array but only for stepper
motors up to 500mA. Does anyone have any ideas on how to construct a
driver for a 1 amp stepper motor? I'd be interested in any ideas.
Regards,
Jim Szymczak
N1RYU
Electrical Engineering
University of New Hampshire
>I wish to use am bs2sx to drive two 12 volt stepper motors. I can do this
>with a uln2003 or uln2803 darlinton transistor array but only for stepper
>motors up to 500mA. Does anyone have any ideas on how to construct a
>driver for a 1 amp stepper motor? I'd be interested in any ideas.
The TI chip (SN754410NE) often mentioned on the list is a direct
replacement for the L293D. It can handle an amp (heatsink it). There's a
tutorial here on how to drive steppers with the L293D, and the TI chip
works the same:
http://www.seattlerobotics.org/encoder/may98/steppers.html
Be sure your stepper really is one amp.
Best, Duncan
We use N-channel MOSFET's for most loads connected to a stamp. If done
correctly, no other components are needed. Try using one with a very low
on-resistance to avoid producing much heat in the MOSFET (under 1 ohm). The
MOSFET should also have a maximum drain current rating several times that of
your maximum peak current, a high voltage rating, and have a built-in
snubber diode connected from the source to the drain.
Good part numbers are: IRF640, IRF840. Both are made by International
Rectifier, and cost about $2 when purchased from DigiKey (www.digikey.com).
We hope this helps you!
John
Original Message
From: Jim Szymczak <szymczak@c...>
To: basicstamps@egroups.com <basicstamps@egroups.com>
Date: Sunday, April 23, 2000 4:05 PM
Subject: Re: [noparse][[/noparse]basicstamps] Transistor selection
>Hello All,
>
>I wish to use am bs2sx to drive two 12 volt stepper motors. I can do this
>with a uln2003 or uln2803 darlinton transistor array but only for stepper
>motors up to 500mA. Does anyone have any ideas on how to construct a
>driver for a 1 amp stepper motor? I'd be interested in any ideas.
>
>Regards,
>Jim Szymczak
>
>N1RYU
>Electrical Engineering
>University of New Hampshire
>
>
>
>
>