output atmega8 to 2n7000

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#1
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Befor conected output of 2N7000(Q1) to load( relays circuit) amplitude
of output pulse(square wave with frequency:2100Hz & 1300Hz fome ATmega8 to Q1) is 8V,but after conected output Q1 to relays circute
output decreased to 4V.how can I prevent to decreas pulse amplitude?schematic

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Last Edited: Thu. Aug 17, 2017 - 07:25 AM
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Well it will won't it?

 

R7 will form a voltage divider with the resistors in your relay network.

'This forum helps those who help themselves.'

 

pragmatic  adjective dealing with things sensibly and realistically in a way that is based on practical rather than theoretical consideration.

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Output of q1 decreased to 4V(oscop connected) , not output of relays circuit.

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Your schematic is a bit hard to read in the post, but I think Brian is talking about the R9/R15, etc, networks.

 

It looks like these end up getting connected across Q1 ?

 

 

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Hello

 

http://fourier.eng.hmc.edu/e84/l...

 

Rest in peace, Kirchhoff

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mostafa147 wrote:
Output of q1 decreased to 4V(oscop connected) , not output of relays circuit.

Use PNP tr with the base connect to your Q1 output via 4k7 resistor and the emitter connect to regulator U4 output and use the collector as output.
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MG

I don't know why I'm still doing this hobby

Last Edited: Mon. Aug 14, 2017 - 02:33 PM
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how can I prevent to decreas pulse amplitude?

Get rid of the resistor dividers (are you trying to reduce the output level or not?).  What are all these different relays supposed to be doing? It's hard to view your schematic.

When in the dark remember-the future looks brighter than ever.

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Thanks,
can I use bc547 or 2n3904 and use emitter as output.collector connected to 12V.I need about 200ma in output.Do need to use capacitor for coupling between two stages?

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I need about 200ma in output

You need to sit down & rethink all about what you are attempting.  How would you draw 0.2A through 10k (that is 2000V drop from your regulator)??!!  Scrap the circuit & basically start over.  You don't even have the bypass caps on your power regulator--quite a bad joke.   Use an opamp with a FET transistor to act as a buffer, providing near-zero drop for your output.  Additionally, use a push-pull pair if you need to sink (to gnd) as well as source current.  You likely don't need any relay's all, the circuit only has one (or two?) output.

 

 another idea- if you need different voltages use an adjustable regulator and your circuit can control the adj pin to set the output high level.

When in the dark remember-the future looks brighter than ever.

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mostafa

Your schematic is like a spaghetti dish.
Can you install this one?    TC427  from Microchip

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Perhaps the OP should tell us what they are trying to do?

'This forum helps those who help themselves.'

 

pragmatic  adjective dealing with things sensibly and realistically in a way that is based on practical rather than theoretical consideration.

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Your schematic is like a spaghetti dish.

That's what happens when you noodle up a schematic

 TC427  from Microchip 

Wonderful for a nice very fast "pulse" of current, its 6 ohms is not so good if you need a precision load voltage at high steady current (think of it as a 6 ohm fet--bleh).

 

Yes, the OP needs to say what the load is & other important details!!

 

When in the dark remember-the future looks brighter than ever.

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Hi   avrcandies

How much do you think I'm nervous?
I'm complaining about this community. Because all of you are talking in "C" language. And you stimulated me to learn this unpleasant language.

Last Edited: Mon. Aug 14, 2017 - 08:02 PM
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I'm complaining about this community

 A plate of spaghetti & bowl of solder soup will take your nervous worries away.  No one has complained yet!

When in the dark remember-the future looks brighter than ever.

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 A plate of spaghetti & bowl of solder soup will take your nervous worries away.  No one has complained yet!

   LOL   

 

  Of course, if the C syntax does not form a loop on my plate.

 

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mostafa147 wrote:
Thanks,
can I use bc547 or 2n3904 and use emitter as output.collector connected to 12V.I need about 200ma in output

Yes you can. But for stable 200mA load you should use darlington not just single BC547. BC547 will sweat for that.
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mostafa147 wrote:
Do need to use capacitor for coupling between two stages?

If you need DC sharp edges pulse then no need for coupling cap. Unless you need it to be AC pulse. And again for 200mA you need a buffer after cap which will be wasted right?
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I'm not sure what you're doing but that's my answer if you ask.
Same with others I hardly understand what your schematic doing.
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MG

I don't know why I'm still doing this hobby

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Brian Fairchild wrote:
Perhaps the OP should tell us what they are trying to do?

 

Yes, that is the key!

 

As many have said already, it is not at all clear what the OP is actually trying to achieve here!

 

http://www.catb.org/~esr/faqs/sm...

 

EDIT

 

The schematic as shown seems to have 3 separate channels.

 

So a good start would be to remove the clutter & complications by showing - and explaining - just one channel.

 

Get one channel working first; then - and only then - move on to extending it to multiple channels...

 

EDIT 2

 

None of this seems to have anything at all to do with the AVR?

 

Last Edited: Tue. Aug 15, 2017 - 06:57 AM
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awneil wrote:
None of this seems to have anything at all to do with the AVR?
Well you say that but if you squint and look at:

 

 

I think I can see "ADC9" or more likely "ADC6", "AREF", "AVCC" "PC6(?) / INT1", "PD4 / <unreadable>", "PD5 / T1", "PD6 / <unreadable>", "PD7 / <unreadable>"

 

So I *think* that looks a bit like some AVR perhaps? Shame it's not possible to make out:

 

 

I think the second last digit there might be a 5 perhaps?

 

EDIT: clearly I was not paying enough attention. Both thread title and #1 both mention "atmega8"

 

Oh and presumably these two inputs:

 

 

are in some way connected to the MCU circuit above?

Last Edited: Tue. Aug 15, 2017 - 10:39 AM
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Yes,  but that is purely incidental to what's being discussed - which is all happening on the other side of the FET...

 

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This is my complete schematic. I want to connect output 1 to first stage from a Transmitter that is a transistor by part P308B(rassuian transistor).amplitude of output should be 5-8 V.

Output 2 goes to one reed relay with amplitude 6-10V.(both are square wave.output 1:1500Hz,output2:12.5Hz). now I want to prevent  decreasing pulses amplitude when Q1 & Q2

connected to loads. when I connected to load output decreased from 8V to 5-6V.

Last Edited: Tue. Aug 15, 2017 - 11:16 AM
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What load resistance do you have? Or, put another way, how much current do you want to deliver to the load?

'This forum helps those who help themselves.'

 

pragmatic  adjective dealing with things sensibly and realistically in a way that is based on practical rather than theoretical consideration.

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max current 200ma

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i send new schematic and explained about load.please see it.

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Your circuit appears ridiculous--is this some kind of joke?   Why do you waste your time on this nonsense?

When in the dark remember-the future looks brighter than ever.

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mostafa147 wrote:

i send new schematic and explained about load.please see it.

I see a schematic, but what is it, what does it attempt to do? 

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Is it me or does the background of the picture in #1 look a lot like Proteus? If so does it really matter what a joke the circuit is because Proteus will not care cheeky I am guessing you could just connect together any random components in any random order and it would do "something". In fact there's probably some point about chimps, typewriters, shakespeare, Proteus and electronic circuits to be made.

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mostafa147 wrote:

This is my complete schematic. I want to connect output 1 to first stage from a Transmitter that is a transistor by part P308B(rassuian transistor).amplitude of output should be 5-8 V.

Output 2 goes to one reed relay with amplitude 6-10V.(both are square wave.output 1:1500Hz,output2:12.5Hz). now I want to prevent  decreasing pulses amplitude when Q1 & Q2

connected to loads. when I connected to load output decreased from 8V to 5-6V


You better do it in real hardware not in Proteus. Even Proteus had a capability to do the work but still real hardware give real result.
And I more confused with 5 megas for freq generator/divider? It's a joke right?
If you need a buffer just try what I suggest using PNP.
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MG

I don't know why I'm still doing this hobby

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It was important for me to produced frequency accurately, so I used 5mega! Have you better suggestions for me? I tested this circuit in real hardware and said its results for you. Please help me about best buffer in outputs q1 & q2.

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So, you need two buffers for your signals that will supply 200mA at 8 volts when fed with 5V signals from your AVRs?

'This forum helps those who help themselves.'

 

pragmatic  adjective dealing with things sensibly and realistically in a way that is based on practical rather than theoretical consideration.

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 now I want to prevent  decreasing pulses amplitude when Q1 & Q2

connected to loads. when I connected to load output decreased from 8V to 5-6V.

...

 Please help me about best buffer in outputs q1 & q2.

Read #9 again.

There you were advised to decrease the value of Q1 Q2 collector resistors. 

Last Edited: Tue. Aug 15, 2017 - 03:07 PM
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MicroGyro wrote:
You better do it in real hardware not in Proteus.

I don't think there was any question that Proteus was giving any problems here - was there?

 

The results from Proteus seemed to be exactly as expected from the circuit as shown?

 

 

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Visovian wrote:
Q1 Q2 collector (sic) resistors

Errr ... they're FETs

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It was important for me to produced frequency accurately, so I used 5mega!

I don't want to be insulting, but your statement makes no sense.  Plus you're shorting the 5 processor outputs all together into one line!!!   

 

Now that you've learned some things and maybe have more experience, it is time to start over with an actual design, not a haphazard arrangement.

When in the dark remember-the future looks brighter than ever.

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Yes ,please

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mostafa147 wrote:
It was important for me to produced frequency accurately, so I used 5mega

Seriously?!

 

Why not just use oscillators of the appropriate frequencies?

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awneil wrote:

Errr ... they're FETs

 

Mea culpa, I hope it's still understandable.

 

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Plus you're shorting the 5 processor outputs all together into one line!!!   ????
No,don't shorting outputs, inputs are from same avr.

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Post #2 outlined the cause. Post #9 suggested a fix. If you want 200mA via a 10k resistor with 8V, then Ohms law won't allow it. Basically you need some form of buffer circuit.
With a bit of creative thinking, i'm sure you could achieve your goal with only one AVR.

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awneil wrote:

I don't think there was any question that Proteus was giving any problems here - was there?

 

The results from Proteus seemed to be exactly as expected from the circuit as shown?

 

 


Just a suggestion to make sure the real hardware works as in the simulator.
Working in real hardware still better.
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MG

I don't know why I'm still doing this hobby

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mostafa147 wrote:
Please help me about best buffer in outputs q1 & q2.

Just try the PNP and your BC547 idea in real hardware. (or test it in sim?) You'll see the differences. It's a simple buffer. Then choose what the best for your needs.
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MG

I don't know why I'm still doing this hobby

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This is quite crazysurprise Are you combining the outputs of a bunch of Megas, through some logic gate combo, to give, what? I can't even imagine the crazy waveform that will be produced. And you know, in the simulator all megas will be in phase, start at exactly the same time, etc. In reality it would be chaos.

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This isn't quite crazy! Output of logic gate is very OK!you don't know my goal of this design.

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mostafa147 wrote:
you don't know my goal of this design.
...and if you cannot or will not explain that goal, no one is going to beat themselves up trying to provide a solution. Garbage in, garbage out.

 

Ross McKenzie ValuSoft Melbourne Australia

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valusoft wrote:

mostafa147 wrote:
you don't know my goal of this design.
...and if you cannot or will not explain that goal, no one is going to beat themselves up trying to provide a solution. Garbage in, garbage out.

 

very anxious to see what that will bring up.

personally I think as protheus is in the loop, this is a school project.

else he should go back to school and actually pay better attention in class.

 

all we can do is sit and wait.......

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mostafa147 wrote:
you don't know my goal of this design.

That is very true, and has been pointed out to you several times!

 

We cannot know the goal of your project unless you explain it to us!

 

Again: http://www.catb.org/~esr/faqs/sm...

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I want to create a train pulse of 1300&2100Hz square wave with duration 12.5Hz.I made 1300&2100 with division 54600Hz by 42&26 scale.train pulse fed to q1 and 12.5Hz fed to q2 for switching in other section.now I need a suitable voltage buffer for output FETs.Is this clear?

Attachment(s): 

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You could do all of that inside one 328.

'This forum helps those who help themselves.'

 

pragmatic  adjective dealing with things sensibly and realistically in a way that is based on practical rather than theoretical consideration.

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do you mean ATmeaga328?
I want to use DIP devices.

Last Edited: Wed. Aug 16, 2017 - 10:55 AM
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Have you tried the suggested buffer? What's the result?
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For the pulse train I think you can use timer to get 1300 and 2100 and set the duration to 12.5Hz (haven't tried it myself). But since you said you managed to get it done then focus on the buffer.
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MG

I don't know why I'm still doing this hobby

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I know my design is not professional! But what is suitable voltage buffer for this circuit ?

This reply has been marked as the solution. 
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You've been given a suggestion already! What have you told us about your requirements? Very little, so we can only guess as to what might be suitable. For the purposes of simulation, you can just use an op-amp in unity gain configuration.

Google op-amp in unity gain configuration     for more information.

Last Edited: Wed. Aug 16, 2017 - 11:22 AM

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