Amplify a signal
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Posts: 46,084
One possible solution is to reverse your logic. What I mean by this is have
your external circuit GROUND the input of the stamp.
Connect a 10k ohm resistor from the stamp input pin to the stamp 5v Vdd
terminal. This is known as a pull-up resistor, you are pulling the input up to 5v.
Connect a simple diode to the stamp input pin. Anode of the diode to the
stamp input, cathode to your external circuit. Have your external circuit ground
the cathode, and have the stamp logic wait for the input to go low instead of
waiting for the input to go high.
What is the voltage level of your external circuit? (voltage when you want it
to trigger the stamp)
I (we) can give you more advice on how to make the external voltage cause the
cathode of the diode to be grounded.
Ken
==================
I need a 5V signal to trigger the BS2 input pin from an external device, but
the only voltage I have is just enough to light up an LED, not enough to
switch a 3V relay. Any input on a simple way to amplify the signal? would an Op-Amp
do the job? any one know of any diagrams posted for op-amps and how to use
them? Thanks guys you're great!
Regards Basil
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your external circuit GROUND the input of the stamp.
Connect a 10k ohm resistor from the stamp input pin to the stamp 5v Vdd
terminal. This is known as a pull-up resistor, you are pulling the input up to 5v.
Connect a simple diode to the stamp input pin. Anode of the diode to the
stamp input, cathode to your external circuit. Have your external circuit ground
the cathode, and have the stamp logic wait for the input to go low instead of
waiting for the input to go high.
What is the voltage level of your external circuit? (voltage when you want it
to trigger the stamp)
I (we) can give you more advice on how to make the external voltage cause the
cathode of the diode to be grounded.
Ken
==================
I need a 5V signal to trigger the BS2 input pin from an external device, but
the only voltage I have is just enough to light up an LED, not enough to
switch a 3V relay. Any input on a simple way to amplify the signal? would an Op-Amp
do the job? any one know of any diagrams posted for op-amps and how to use
them? Thanks guys you're great!
Regards Basil
[noparse][[/noparse]Non-text portions of this message have been removed]
Comments
Regards Basil
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[noparse][[/noparse]Non-text portions of this message have been removed]
How's it going?
If you've got enough input signal to operate an LED, use a
transistor to switch the input.
Put a 10k pullup( ie to +5 v ) resistor on the stamp pin. Connect
collector of a 2N2222 transistor to the stamp pin as well. Connect
transistor emitter to 0 volts.
Connect your field signal to the base of the transistor through a
current limiting resistor of about 1 K ( you may have to experiment
with this value ).
When your field signal is high, the stamp pin will be low and
vice versa.
Regards,
Tom Sisk
--- In basicstamps@yahoogroups.com, smartdim@a... wrote:
> One possible solution is to reverse your logic. What I mean by this
is have
> your external circuit GROUND the input of the stamp.
>
> Connect a 10k ohm resistor from the stamp input pin to the stamp 5v
Vdd
> terminal. This is known as a pull-up resistor, you are pulling the
input up to 5v.
>
> Connect a simple diode to the stamp input pin. Anode of the diode
to the
> stamp input, cathode to your external circuit. Have your external
circuit ground
> the cathode, and have the stamp logic wait for the input to go low
instead of
> waiting for the input to go high.
>
> What is the voltage level of your external circuit? (voltage when
you want it
> to trigger the stamp)
>
> I (we) can give you more advice on how to make the external voltage
cause the
> cathode of the diode to be grounded.
>
> Ken
>
> ==================
>
>
> I need a 5V signal to trigger the BS2 input pin from an external
device, but
> the only voltage I have is just enough to light up an LED, not
enough to
> switch a 3V relay. Any input on a simple way to amplify the signal?
would an Op-Amp
> do the job? any one know of any diagrams posted for op-amps and how
to use
> them? Thanks guys you're great!
> Regards Basil
>
>
> [noparse][[/noparse]Non-text portions of this message have been removed]
thanks you for responding. The signal turned out to be a bit more complicated than I thought. I had a friend locally help me out. He sent me an email today, it said:
"Basil, It was more challenging than I expected, but it's ready now.
(Surprise: the buzzer off condition is 8 volts dc, and the buzzer on
condition is 16 volts ac, with very limited current drive capability !!)"
I shall see him over the week end and follow up.
Tom, thanks again for solving the 8-7 bit printer problem for me !!!
The last part of the design is to detect when the receipt printer prints1
that is to activate a relay whenever a data line is sent to the printer to be printed out and this will trigger an input pin on the stamp. Have you dealt with this before? know of an easy way? I was going to tap into the printer motor that feeds the paper for a second. I don't need the printer to print at that time, but I do need the detection when the serial data is sent to the printer.
Tom thanks always for your help.
Best regards
Basil
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