How to use function generator to get 0-5V TTL signal

[scdoro]

Hi, I have only this function generation that can only give me a -ve to +ve signal. This isn't any offset funtion or TTL function. May I know how to make use of this function generator to give me a 0-5 Square wave signal ?
Is there any way ? ( etc built a very simple cct ) ?
thanks

 

[IanP]

comparator opamp connect ttl

You can use a resistor, say, 1kΩ, and 4.7V - 5.1V zener diode. This will cut off the negative voltages and set the maximum at 4.7-5.1V level ..

 

[scdoro]

ttl signal generator

but will the frequency be affect after going thro the zener diode ?

 

[IanP]

diode to 5v ttl

If you are worried about frequency response you can always use 5 or 6 ultrafast diodes connected in series ( and 1 in opposite direction to cut off negative voltage) to overcome this problem ..

 

[scdoro]

ttl 0-5v

Hi,
If i use the diode connected in series, then the voltage across will be 0.7v but i need a voltage of 5 V to have a logic 1. ... Logic 0 is 0V, Logic 1 is 5 V.
May I know how to overcome this ? Thanks.

Added after 49 seconds:

and do i need to use Capacitors or any resister? If so, how to connect them ? Thanks

 

[IanP]

5v ttl signal

You don't need exactly 5V for logic H:

TTL gates operate on a nominal power supply voltage of 5 volts, +/- 0.25 volts. Ideally, a TTL "high" signal would be 5.00 volts exactly, and a TTL "low" signal 0.00 volts exactly. However, real TTL gate circuits cannot output such perfect voltage levels, and are designed to accept "high" and "low" signals deviating substantially from these ideal values. "Acceptable" input signal voltages range from 0 volts to 0.8 volts for a "low" logic state, and 2 volts to 5 volts for a "high" logic state. "Acceptable" output signal voltages (voltage levels guaranteed by the gate manufacturer over a specified range of load conditions) range from 0 volts to 0.5 volts for a "low" logic state, and 2.7 volts to 5 volts for a "high" logic state).

All you need is a resistor (depending on the +/- max voltage); most likely 1kΩ will be just fine. This resistor has to be connected between your function generator and this set of diodes ..

Added after 12 minutes:

Attached is the circuit ..

 

[scdoro]

building a 0-5v ttl trigger circuit

may i know
1) why do i need to add 6 diode in a series ?? how come not one ??
2) what u mean by ultrafast diode ? can 1N4148 can be use ?
thanks a lot

 

[IanP]

5 v/ttl

6 x 1N4148 will be good for this application and will give you 6 x 0.7V=4.2V threshold which you need for logic H (TTL, CMOS, ..etc) ..

 

[scdoro]

ttl-signal

Hi,
I have built the cct u recommended. But there is still a negative voltage of 1V.. i guess is due to the diode in the opppositve direction.May I know how to overcome this problem cuz i can't have negative at all for my TTL ? Thanks

 

[IanP]

0-5v signal generator

Connect 1 diode before the resistor. This will cut off all negative voltages ..

Added after 11 minutes:

or build a level translator as per attached drawing ..

 

[scdoro]

invert low signal ttl

hi, in practical, there will still be a -0.7V drop across that diode that cut off the negative voltage.. so which mean.. the min signal won't be 0V it will be -0.7V cuz of the voltage drop across the diode . hmmm.. is there a way to overcome this ?
thanks

 

[flatulent]

output 5v ttl to 0-5v

use a comparator with a TTL output.

 

[IanP]

ttl сигнал

The last circuit (with transistor) will not produce any negative output: it is approx. 0-5V.
The diode protects the base-emiter junction against reverse (negative) voltages and has nothing to do with the output level ..

 

[suromenggolo]

what is a ttl signal

uses germanium diode, but it will across voltage -0,2V. it is still problem.?
if still it, you must uses transistor.

 

[scdoro]

build ttl signal

Hi, i have try using a LM339 comparator.. but i realise that the frequency is increased by many time which i do not want that . n oso i still get a -ve voltage of ard 1V .. is there a way to overcome this ? thanks

 

[gidimiz]

ttl connect to 5v

Hi,

Hi, I have only this function generation that can only give me a -ve to +ve signal. This isn't any offset funtion or TTL function. May I know how to make use of this function generator to give me a 0-5 Square wave signal ?
Is there any way ? ( etc built a very simple cct ) ?
thanks

Can you post the type, circuit or something. maybe we are all going the wrong way here. Do you have a user manual or something that we can see what you have and what you can get out of it?

From what you wrote, an easy way is to pass the signal usign a small capacitor ( remove and DC offset. Add DC offset for what ever you need to ( move it -ve in the possative direction ), and pass it using a simple Schmitt Trigger amplifier
**broken link removed**.

So, if this wont work. please post the User Manual or the schamatic of the generator.

Good luck.

 

[pic16f876]

ttl gates circuits

You should use a MAX232 RS232-TTL level converter. Its a bit more complex than diodes, and the signal is inverted, but may do the job. Be carefull, the frequency is limited to 120 KHz.

 

[irfansyah]

ttl level conversion zener diode

Why don't you use a comparator (an opamp)?

Connect the inverting pin of opamp to ground, and the non-inverting pin to your function generator. Use 5 volts for the Vcc for opamp, and GND for the other power supply pin polarity. Use an LF357 maybe? (this opamp is relatively good, i think).

 

[scdoro]

create a ttl signal with 5v power

Hello,
Thanks so much.. I manage to get it done with the help of u guys
..juz that the frequency is only up to 15Khz... but at least i can proceed with my proj for the time being.
My proj needs up to 50MHz
Thanks u all so much