Mini Digital Thermometer Project

[gnlds]

Hi, I have a thermometer project and I need help. I created a few circuits with different way. Although it seems correct, they didn't work. I added different versions of my project, please help me to solve this problem.

Thank you !

You can download .DSN files:
**broken link removed**
http://hotfile.com/dl/45355206/40e5448/Projects.rar.html

 

[ericgibbs]

Hi, I have a thermometer project and I need help. I created a few circuits with different way. Although it seems correct, they didn't work. I added different versions of my project, please help me to solve this problem.

Thank you !

hi,
On the first circuit ADC_7447, the adc outputs a 8 bit binary value, you cannot split that into two lines of 4 to drive a 7447 decoder.

On the second circuit ICL_LM35 what are those two white boxes.??

The LM35 simulator, what output voltage is that set for.?

You can download .DSN files:
**broken link removed**
Hotfile.com: One click file hosting: Projects.rar

hi,
On the first circuit ADC_7447, the adc outputs a 8 bit binary value, you cannot split that into two lines of 4 to drive a 7447 decoder.

On the second circuit ICL_LM35 what are those two white boxes.??

The LM35 simulator, what output voltage is that set for.?

 

[gnlds]

*So, how can I show temperature in two displays? (45 C for example)

*White boxes are 7-Segment Display(Common Anode)

*0 C - 50 C enough for me. I tried to set LM35 for this.

 

[ericgibbs]

*So, how can I show temperature in two displays? (45 C for example)

*White boxes are 7-Segment Display(Common Anode)

*0 C - 50 C enough for me. I tried to set LM35 for this.

hi,
The 8 bit binary to BCD is a common problem, you need to convert the 8bits to two BCD bytes, its not simple, I will check the Forums for you.

The ICL7107 has constant current drivers for the LED's, you should not have that 1K resistor from the supply line, its a direct connection.

The LM35 outputs 10mV/Cdeg from +2C thru +150C

EDIT:
Look at this link also search the Forums for binary to bcd

**broken link removed**

 

[gnlds]

After your message, I searched on Google and I saw this link too. But I have to do this project without PIC.

 

[ericgibbs]

After your message, I searched on Google and I saw this link too. But I have to do this project without PIC.

hi,
The simple way is the ICL7107, it outputs BCD data directly to the LED's.
What problems do you have with the 7107 project.???

 

[gnlds]

So, I'll concentrate on second circuit. Actually it seems normal and no warning, but displays don't show anything.

 

[ericgibbs]

So, I'll concentrate on second circuit. Actually it seems normal and no warning, but displays don't show anything.

hi,
The LED's should show '00', with no input signal. Did you remove those 1k resistors from the CA LED's.??

 

[gnlds]

Yes, i removed.

 

[ericgibbs]

Yes, i removed.

Do the LED's display '00', if not check your wiring.????

 

[gnlds]

I created a new project. Displays show something but changeable. You must see on ISIS. JPEG file shows the LM35. PDF file shows circuit.

.DSN file
Hotfile.com: One click file hosting: LProject.DSN

Thank you.

 

[ericgibbs]

I created a new project. Displays show something but changeable. You must see on ISIS. JPEG file shows the LM35. PDF file shows circuit.

.DSN file
Hotfile.com: One click file hosting: LProject.DSN

Thank you.

hi,
What range of full scale voltage have you set the 7107 too.?
Dont forget if, you have set it to 199.9 mV full scale and as you are using only the lowest two digits they will show 0.0 to 9.9mV so they will change randomly
What temperature range do you want to display.????

 

[gnlds]

Yes it's changing randomly. I want to show 0 - 50 range with two displays (First and second digit of temperature).

 

[crutschow]

Here's one thread on a https://www.electro-tech-online.com/threads/8-bit-binry-to-decimal-circuit.95009/.

 

[ericgibbs]

Yes it's changing randomly. I want to show 0 - 50 range with two displays (First and second digit of temperature).

hi,
For a temperature range of +2C to +50Cdeg, thats 20mV to 500mV.
What voltage display range have you set the 7107 for.???
As I said in my previous post, if its set for +199.9mV [thats the basic range] then as you are only using the least two digits on the 7107, you have a problem.
example: 10C is 100mV so you will see only '00' on the display, only temperatures less than 10C will display correctly.

I would recommend that you add another LED and set the 7107 for 1.999V, so 50C would display as 0.500, set the decimal point to 050.0

 

[gnlds]

I tried to set 7107 for 20V DC(I changed from ICL7107 typical 200mV application).

Now I'm trying with 4 displays. If it doesn't work I'll try typical application with 4 displays.

 

[ericgibbs]

I tried to set 7107 for 20V DC(I changed from ICL7107 typical 200mV application).

Now I'm trying with 4 displays. If it doesn't work I'll try typical application with 4 displays.

OK, let me know how it goes, if you get stuck, I will help you calculate the 7107 component values.