Thermometer design with 2 Leds

I

Inbroker

Guest
Hi guys.I have an assignement to do and I am having some difficulties.
I have to make a thermometer using a thermical sensor that gives
analog output variable to the temperature, pass it through an analog
to digital (A/D) converter and drive the digital output to two leds
who will present the temperature.My main difficulty is how to drive
the two leds.Any ideas.With no use of a PIC.THanks in advance
 
On 27 Apr 2004 15:34:46 -0700, inbroker2002@yahoo.com (Inbroker)
wrote:

Hi guys.I have an assignement to do and I am having some difficulties.
I have to make a thermometer using a thermical sensor that gives
analog output variable to the temperature, pass it through an analog
to digital (A/D) converter and drive the digital output to two leds
who will present the temperature.My main difficulty is how to drive
the two leds.Any ideas.With no use of a PIC.
Click to expand...
---
Two LED lamps, or two LED seven-segment displays, or two LED whats?

--
John Fields
 
On Tue, 27 Apr 2004 18:14:02 -0500, John Fields wrote:

On 27 Apr 2004 15:34:46 -0700, inbroker2002@yahoo.com (Inbroker)
wrote:

Hi guys.I have an assignement to do and I am having some difficulties.
I have to make a thermometer using a thermical sensor that gives
analog output variable to the temperature, pass it through an analog
to digital (A/D) converter and drive the digital output to two leds
who will present the temperature.My main difficulty is how to drive
the two leds.Any ideas.With no use of a PIC.

---
Two LED lamps, or two LED seven-segment displays, or two LED whats?
Click to expand...
Probably two LED whats. I always have problems driving those after
designing the complex stuff.
--
Best Regards,
Mike
 
On Tue, 27 Apr 2004 20:00:34 -0400, Active8 wrote:

On Tue, 27 Apr 2004 18:14:02 -0500, John Fields wrote:

On 27 Apr 2004 15:34:46 -0700, inbroker2002@yahoo.com (Inbroker)
wrote:

Hi guys.I have an assignement to do and I am having some difficulties.
I have to make a thermometer using a thermical sensor that gives
analog output variable to the temperature, pass it through an analog
to digital (A/D) converter and drive the digital output to two leds
who will present the temperature.My main difficulty is how to drive
the two leds.Any ideas.With no use of a PIC.

---
Two LED lamps, or two LED seven-segment displays, or two LED whats?

Probably two LED whats. I always have problems driving those after
designing the complex stuff.
Click to expand...
Probably need 2 BCD to 7-segment decoders. Going from A/D out to BCD
will be more fun but we can't start playing without more info like
temp range, F or C, etc. I'd assume fahrenheit since below freezing
is still a positive number handled with 2 digits.
--
Best Regards,
Mike
 
The idea is not mine, I saw it firstly on a HP printer and applied several
times.
When you have to tell more on a single led, you can use MORSE CODE.
piero



Active8 wrote:

On Tue, 27 Apr 2004 20:00:34 -0400, Active8 wrote:

On Tue, 27 Apr 2004 18:14:02 -0500, John Fields wrote:

On 27 Apr 2004 15:34:46 -0700, inbroker2002@yahoo.com (Inbroker)
wrote:

Hi guys.I have an assignement to do and I am having some difficulties.
I have to make a thermometer using a thermical sensor that gives
analog output variable to the temperature, pass it through an analog
to digital (A/D) converter and drive the digital output to two leds
who will present the temperature.My main difficulty is how to drive
the two leds.Any ideas.With no use of a PIC.

---
Two LED lamps, or two LED seven-segment displays, or two LED whats?

Probably two LED whats. I always have problems driving those after
designing the complex stuff.

Probably need 2 BCD to 7-segment decoders. Going from A/D out to BCD
will be more fun but we can't start playing without more info like
temp range, F or C, etc. I'd assume fahrenheit since below freezing
is still a positive number handled with 2 digits.
--
Best Regards,
Mike
Click to expand...
 
Presumably you mean two seven-segment LED displays? I'm all for
minimalist human interfaces, but two LEDs is probably stretching it a
bit.

Have a look for 7-segment decoder-driver chips. You should be able to
find something in some of the common logic families. Beware that you
may also have to convert from binary to decimal, if you want the
display in decimal and not octal or hex. You can avoid that problem
by using an ADC with decimal output, and many of those already have
7-segment outputs. You're likely to find something interesting on the
Maxim site.

Cheers,
Tom

inbroker2002@yahoo.com (Inbroker) wrote in message news:<ecf13011.0404271434.388e2271@posting.google.com>...
Hi guys.I have an assignement to do and I am having some difficulties.
I have to make a thermometer using a thermical sensor that gives
analog output variable to the temperature, pass it through an analog
to digital (A/D) converter and drive the digital output to two leds
who will present the temperature.My main difficulty is how to drive
the two leds.Any ideas.With no use of a PIC.THanks in advance
Click to expand...
 
Yes two 7 segment leds.The problem is how to transform the binary
output of The A/D to I don't know what (maybe BCD code) to drive the
two leds.I know how to drive the 2 leds from BCD code (see 7447
family).It is Celcius
 
Yes it is 7-segment leds.My problem is how to drive the binary output
of A/D converter to I don't know (maybe BCD code) to drive the 2
leds.I know how to drive the leds from BCD code.
 
On 27 Apr 2004 15:34:46 -0700, inbroker2002@yahoo.com (Inbroker)
wrote:

Hi guys.I have an assignement to do and I am having some difficulties.
I have to make a thermometer using a thermical sensor that gives
analog output variable to the temperature, pass it through an analog
to digital (A/D) converter and drive the digital output to two leds
who will present the temperature.My main difficulty is how to drive
the two leds.Any ideas.With no use of a PIC.THanks in advance
Click to expand...
---
Assuming that you're talking about a parallel-output ADC, probably the
easiest way to do it is to scale the output of your ADC so that at 0°
into the sensor the output of the ADC will be
0000 0000, and for for 99° the output of the ADC will be 0110 0011.

Then, burn a binary-to-BCD lookup table into EPROM and use the EPROM's
outputs to drive two BCD to seven-segment decoders.

Like this:


+------+ +V
+----| | +-----+ +-----+ |
| | | | | | |--/4--[4511]---[R]--[DISPLAY>]--+
[SENSOR] | GAIN |--| ADC |--| LUT | |
| |STAGE | | | | |--/4--|4511]---[R]--[DISPLAY>]--+
+----| | +-----+ +-----+
+------+


The binary-to-BCD conversion is straightforward, and you send the
outputs of the ADC to the address inputs of the EPROM and use the
outputs of the EPROM to drive the 4511's.

The lookup table should look like this in hexadecimal:

ADDRESS DATA
--------+------
00 00
01 01
02 02
03 03
04 04
05 05
06 06
07 07
08 08
09 09
0A 10
0B 11
0C 12
. .
. .
. .
63 99


If you're not allowed to burn an EPROM, then you could take the binary
output from your ADC and load it into a binary down counter at the
same time that you're clearing a BCD up counter and latching the old
value contained in the BCD couter into the display drivers, then use
the same clock to run both counters. That way, when the binary
counter gets to zero the BCD counter will have accumulated the number
loaded into the binary counter, and its (the BCD counter) output can
be latched into the BCD to seven-segment decoders which will display
the contents of the ADC (the temperature) in BCD).

Or, you could find an ADC with a BCD output...

--
John Fields
 
"John Fields" <jfields@austininstruments.com> schreef in bericht
news:jk7890h3vndu5s4eapg88reed2gjkd4r8n@4ax.com...

[snip]

Or, you could find an ADC with a BCD output...
Click to expand...
Yes, something like that good old ICL7107 (?)

--
Thanks, Frank.
(remove 'x' and 'invalid' when replying by email)
 
On Sun, 2 May 2004 01:17:37 +0200, "Frank Bemelman"
<f.bemelmanx@planet.invalid.nl> wrote:

"John Fields" <jfields@austininstruments.com> schreef in bericht
news:jk7890h3vndu5s4eapg88reed2gjkd4r8n@4ax.com...

[snip]

Or, you could find an ADC with a BCD output...

Yes, something like that good old ICL7107 (?)
Click to expand...
---
Yup! :)

--
John Fields
 
Inbroker wrote:
Hi guys.I have an assignement to do and I am having some difficulties.
I have to make a thermometer using a thermical sensor that gives
analog output variable to the temperature, pass it through an analog
to digital (A/D) converter and drive the digital output to two leds
who will present the temperature.My main difficulty is how to drive
the two leds.Any ideas.With no use of a PIC.THanks in advance
Click to expand...
Two digits is not a lot of precision so you can do the analog
subtraction of the largest multiple of the voltage corresponding to 10o
that does not cause underflow- then latch the multiplier digit into the
MSD latch/decoder/driver, and the A/D output into the LSD
latch/decoder/driver.
 
"John Fields" <jfields@austininstruments.com> wrote in message
news:2he890pug2f6jtamgu865sl0e470pbvut4@4ax.com...
On Sun, 2 May 2004 01:17:37 +0200, "Frank Bemelman"
f.bemelmanx@planet.invalid.nl> wrote:

"John Fields" <jfields@austininstruments.com> schreef in bericht
news:jk7890h3vndu5s4eapg88reed2gjkd4r8n@4ax.com...

[snip]

Or, you could find an ADC with a BCD output...

Yes, something like that good old ICL7107 (?)

---
Yup! :)
Click to expand...
LM35 and a DPM.

Two Parts!

:)
Cheers!
Rich
 
On Tue, 04 May 2004 18:17:45 GMT, "Rich Grise" <null@example.net>
wrote:

"John Fields" <jfields@austininstruments.com> wrote in message
news:2he890pug2f6jtamgu865sl0e470pbvut4@4ax.com...
On Sun, 2 May 2004 01:17:37 +0200, "Frank Bemelman"
f.bemelmanx@planet.invalid.nl> wrote:

"John Fields" <jfields@austininstruments.com> schreef in bericht
news:jk7890h3vndu5s4eapg88reed2gjkd4r8n@4ax.com...

[snip]

Or, you could find an ADC with a BCD output...

Yes, something like that good old ICL7107 (?)

---
Yup! :)


LM35 and a DPM.

Two Parts!
Click to expand...
---
Well, not really... the DPM isn't monolithic.

--
John Fields
 
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