hello everyone,

i am working on a project to make an digital thermometer without using microcontroller . But i don't have any idea ,for where should i start .Can someone help me

 

Here's a 'Living room Thermometer' from the master himself, Jim Williams:

 

Hello,

Is this a school project?
What parts are you allowed to use?
Can a voltmeter chip be used?
Can a temperature sensor chip be used?
How should the temperature be displayed, as bargraph or in numbers?
What range of temperature should be measured?

Bertus

 

You can follow this tutorial. https://www.instructables.com/Make-a-digital-thermometer/

 

This is a classic school exercise in introductory electronics.
Begin with a block diagram that shows the flow of data.



Next, make a list of all the requirements of the project.

 

hello everyone,

i am working on a project to make an digital thermometer without using microcontroller . But i don't have any idea ,for where should i start .Can someone help me

traditional way to display digital value is to use counter. so number of counted pulses equals displayed value. for more details lookup retro frequency counters.

if you want value to update dynamically, you need to periodically reset counter and let it count again. to avoid flicker, keep old value displayed until count is complete and then transfer new value in an instant.

the next part is to generate pulses - you need something that counter can count. that means you need clock oscillator (OSC1).

the next part is gate. it is allowing you to control when pulses from oscillator can reach counter, basically when to count and when to do something else (transfer value and reset counter). the longer gate is open, more pulses get through it and displayed value is larger. if gate is always closed, counter will periodically get reset and when that value is transferred to display, you will see zero.

congratulation, you (almost) have digital readout. just need transfer (latch) and reset counter signals.

now you need to get data from some sensor and use it to control the gate. suppose you measure temperature using thermistor. suppose this thermistor is part of (another) oscillator, then temperature change will affect frequency of this oscillator (OSC2).

so when OSC2 output is high:
display should be frozen (no value changes, avoid flicker).
counter should run and count pulses

when OSC2 output changes to low:
generate pulses to
a) transfer counted value and latch it
b) reset counter (ready for next operation).

that was for analog sensors...

and... if the sensor itself is digital, you need to build circuitry that will generate necessary signals to get the value out.

as already stated, you need to narrow down things considerably.

 

There is a link in this site that accesses the old popular site that accesses the old popular electronics magazines. They have had more than one digital thermometer in their projects list. A lot of them used a thermistor or a diode as the sensor. Diodes change their knees slightly according to their temperature, which is used to measure the temperature.