Stamps in automotive setting

Archiver

My common sense tells me that my questions must be already be answered
and written up someplace, but I couldn't find them.

For the BS2:

First, the spec says that the power supply can up to 15v--is it
tolerant of the noise or spikes that one might find in a car? Or is
it required to add a filter or zener to the power input?

Secondly, along the same theme, if I am trying to read input from
automotive levels, ie something that goes between 12V and gnd, what
are the recommended input resistors?

Advice or a pointer to an application note, or whatever, will be much
appreciated.

John

Archiver

John, I have used a stamp directly from the vehicle battery several times,
and despite the noisy evironment I have not had trouble.

The 0 to 12 volt signals from the vehicle CANNOT directly be read by the
stamp. A quick and dirty way to convert the 12 volt signals to 5 volt signals,
(something the stamp wants for inputs) is to get ahold of some 2n3904 or 2n2222
NPN transistors.....


Connect the base lead of the transistor to the 12 volt sighal THROUGH 47k
ohms.

Connect the emitter lead to ground

Connect the collector lead to +5 volts THROUGH 10k ohms.

Connect the collector lead to the stamp input pin THROUGH 220 ohms.

When the 12 volt signal is at 12 volts, the stamp input will read logic zero.

When the 12 volt signal is at 0 volts, the stamp input will read logic one.

The values and method a"quick and dirty" and they will work. There are a
variety of other methods to provide much better protection for your stamp should

something fail. Also, the car ground, stamp ground and the ground for any
signals must be common.

I am sure other Stampers will give alternative ideas, like opto isolators and
a DC to DC converter to run the stamp.

Ken

---

My common sense tells me that my questions must be already be answered
and written up someplace, but I couldn't find them.

For the BS2:

First, the spec says that the power supply can up to 15v--is it
tolerant of the noise or spikes that one might find in a car? Or is
it required to add a filter or zener to the power input?

Secondly, along the same theme, if I am trying to read input from
automotive levels, ie something that goes between 12V and gnd, what
are the recommended input resistors?

Advice or a pointer to an application note, or whatever, will be much
appreciated.

John


[noparse][[/noparse]Non-text portions of this message have been removed]

Archiver

Thanks, that's exactly what I needed.

John


smartdim@a... wrote:
> John, I have used a stamp directly from the vehicle battery several times,
> and despite the noisy evironment I have not had trouble.
>
> The 0 to 12 volt signals from the vehicle CANNOT directly be read by the
> stamp. A quick and dirty way to convert the 12 volt signals to 5 volt signals,

> (something the stamp wants for inputs) is to get ahold of some 2n3904 or
2n2222
> NPN transistors.....
>
>
> Connect the base lead of the transistor to the 12 volt sighal THROUGH 47k
> ohms.
>
> Connect the emitter lead to ground
>
> Connect the collector lead to +5 volts THROUGH 10k ohms.
>
> Connect the collector lead to the stamp input pin THROUGH 220 ohms.
>
> When the 12 volt signal is at 12 volts, the stamp input will read logic zero.
>
> When the 12 volt signal is at 0 volts, the stamp input will read logic one.
>
> The values and method a"quick and dirty" and they will work. There are a
> variety of other methods to provide much better protection for your stamp
should
> something fail. Also, the car ground, stamp ground and the ground for any
> signals must be common.
>
> I am sure other Stampers will give alternative ideas, like opto isolators and
> a DC to DC converter to run the stamp.
>
> Ken