A/D Converter related question - Electronic Circuits Projects Diagrams Free

appleseed · 27th August 2006, 12:07 AM

Hello everyone...

Take a look at this A/D converter circuit. I have this question:
What is the purpose of the 74374? And What is the Bus Enable Port?

Papabravo · 27th August 2006, 02:19 AM

The 74374 is a transparent latch which holds the output data from the counters. The bus enable port controls the three state drivers on the outputs. When it is low the the outputs are high or low according to their contents. When it is high the outputs are in a high impedance condition and do not source or sink current. Multiple tri-state outputs can be connected together as long as only one at a time is enabled.

That Forrest Mimms sure is a bright guy -- isn't he?

appleseed · 27th August 2006, 11:19 AM

ok so what is it exactly that the circuit transforms into a digital signal?

**Nigel Goodwin** · 27th August 2006, 12:20 PM

Quote:

Originally Posted by appleseed

ok so what is it exactly that the circuit transforms into a digital signal?

Like any A2D it takes a DC voltage at the input, and converts it to a digital representation of that voltage. Presumablt it's got a 5V range?, so zero volts will give b'00000000' and 5V will give b'11111111' outputs.

It's a very crude project though, it would be a lot simpler to do it in other ways.

Dr.EM · 27th August 2006, 12:35 PM

I put up another post about using an ADC0804 for a possible project. It is about £3 and probably works better? Although this is an interesting design.

Papabravo · 27th August 2006, 02:50 PM

The original circuit (circa. 1973) does show the internal works. It would of course be impractical to use in an actual application.

appleseed · 28th August 2006, 07:41 PM

in what external means can one demonstrate the output?

Marks256 · 28th August 2006, 08:51 PM

LEDs would work.

appleseed · 30th August 2006, 07:06 PM

what if one connected the output data from the counters directly to leds?
What would be the problem with that?

And something else, would the current from the 74374 be big enough to light the leds?

Dr.EM · 30th August 2006, 09:47 PM

Use larger than normal resistor values (1.5k?), the LEDs may be dim, but you should get what you need from it.

appleseed · 31st August 2006, 06:52 PM

i think a normal resistor would be 150Ω

appleseed · 3rd September 2006, 01:23 AM

b2 spice doesnt have the tl507. maybe its under another name?
or does anyone know where i can find part libraries?

appleseed · 3rd September 2006, 10:55 AM

or at least does anyone know what chip should i use instead of the tl507 because i cant find it anywhere?

**Nigel Goodwin** · 3rd September 2006, 11:49 AM

Quote:

Originally Posted by appleseed

or at least does anyone know what chip should i use instead of the tl507 because i cant find it anywhere?

It's a antique chip, so it's not likely to be available - but as you've never suggested what you want to do, how can we make suggestions?.

appleseed · 4th September 2006, 01:08 AM

the design i attached in this thread... thats what i want to do. but i need to replace the tl507.

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27th August 2006, 02:19 AM	(permalink)
Papabravo	The 74374 is a transparent latch which holds the output data from the counters. The bus enable port controls the three state drivers on the outputs. When it is low the the outputs are high or low according to their contents. When it is high the outputs are in a high impedance condition and do not source or sink current. Multiple tri-state outputs can be connected together as long as only one at a time is enabled. That Forrest Mimms sure is a bright guy -- isn't he?

27th August 2006, 11:19 AM	(permalink)
appleseed	ok so what is it exactly that the circuit transforms into a digital signal?

27th August 2006, 12:35 PM	(permalink)
Dr.EM	I put up another post about using an ADC0804 for a possible project. It is about £3 and probably works better? Although this is an interesting design. __________________ Angry!? I'm absolutely electrolytic! Will have to make do with myspace now I guess...

27th August 2006, 02:50 PM	(permalink)
Papabravo	The original circuit (circa. 1973) does show the internal works. It would of course be impractical to use in an actual application.

28th August 2006, 07:41 PM	(permalink)
appleseed	in what external means can one demonstrate the output?

28th August 2006, 08:51 PM	(permalink)
Marks256	LEDs would work. __________________ There is no "I" in "team", unless Apple makes it... Then it would be iTeam.

30th August 2006, 07:06 PM	(permalink)
appleseed	what if one connected the output data from the counters directly to leds? What would be the problem with that? And something else, would the current from the 74374 be big enough to light the leds?

30th August 2006, 09:47 PM	(permalink)
Dr.EM	Use larger than normal resistor values (1.5k?), the LEDs may be dim, but you should get what you need from it. __________________ Angry!? I'm absolutely electrolytic! Will have to make do with myspace now I guess...

31st August 2006, 06:52 PM	(permalink)
appleseed	i think a normal resistor would be 150Ω

3rd September 2006, 01:23 AM	(permalink)
appleseed	b2 spice doesnt have the tl507. maybe its under another name? or does anyone know where i can find part libraries?

3rd September 2006, 10:55 AM	(permalink)
appleseed	or at least does anyone know what chip should i use instead of the tl507 because i cant find it anywhere?

4th September 2006, 01:08 AM	(permalink)
appleseed	the design i attached in this thread... thats what i want to do. but i need to replace the tl507.