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Function Generator Simulation (Need Help)

### Author Topic: Function Generator Simulation (Need Help)  (Read 7974 times)

#### xsumirx

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• Posts: 21
##### Re: Function Generator Simulation (Need Help)
« Reply #14 on: February 11, 2012, 02:41:50 PM »
The circuit works perfectly and is very reliable.

Thankyou Audioguru

This is that answer which I was want to listen in short

#### xsumirx

• Newbie
• Posts: 21
##### Re: Function Generator Simulation (Need Help)
« Reply #15 on: February 11, 2012, 03:24:43 PM »
One thing I still did not understand..... That

Current is depend on load resistance.  by changing the Load Resistance only the current can be controlled.

Can you tell me, How we are controlling the current here ?

How we get the desired current output independently to load resistance here in the circuit ?

I am completely unknown from this fact.

Plz..

#### audioguru

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##### Re: Function Generator Simulation (Need Help)
« Reply #16 on: February 11, 2012, 06:12:36 PM »
The maximum amount of output current is adjusted with the current regulation pot.
When the output current tries to exceed the setting of the current regulation pot then the output voltage is reduced until the current is what was set.

Example: Set the current regulation pot for a max current of 2A. Set the output voltage to 20V.
Now if the load resistance is 10 ohms, 2A will flow and the output will remain at 20V.
If the load is 8 ohms then the output voltage will be reduced to 16V.
if the load is 1 ohm then the output voltage will be reduced to 2V.

#### xsumirx

• Newbie
• Posts: 21
##### Re: Function Generator Simulation (Need Help)
« Reply #17 on: February 11, 2012, 09:37:22 PM »
your answer take me to 2 different confusion...

1st
if the load resistance is 20ohm , then how 40v will flow through the load, so the maximum limit of Vout is just 30v.

2nd
if the circuit will do like this then how we will get our desired Vout at the o/p end, in this manner only one thing can be controlled by us voltage or current ?

Plz...

#### audioguru

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##### Re: Function Generator Simulation (Need Help)
« Reply #18 on: February 11, 2012, 11:24:08 PM »
1) if the load resistance is 20ohm, then how 40v will flow through the load, so the maximum limit of Vout is just 30v.
It is not a generator, it is a 30V max power supply.
If the voltage is set to 30V, the max current regulation is set to 1.5A or more and it has a 20 ohm load then the current is 30V/20 ohms= 1.5A. The output voltage cannot exceed 30V.

Quote
2) if the circuit will do like this then how we will get our desired Vout at the o/p end, in this manner only one thing can be controlled by us voltage or current?
You set the voltage up to 30V then you set the maximum output current up to 3A. When the output current tries to exceed the current setting then the output voltage is reduced until the current is what is the setting.

#### xsumirx

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• Posts: 21
##### Re: Function Generator Simulation (Need Help)
« Reply #19 on: February 13, 2012, 03:58:27 PM »
okkk...Thanx

Tell me one more thing !!!
Will BD136 will work instead of BD140.

In power supply section

#### audioguru

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##### Re: Function Generator Simulation (Need Help)
« Reply #20 on: February 13, 2012, 05:00:37 PM »
Will BD136 will work instead of BD140 in power supply section
The power supply does not use a BD136 or BD140 PNP transistor.
Instead it uses a BD139 NPN transistor but a BD137 NPN transistor will work fine.

#### xsumirx

• Newbie
• Posts: 21
##### Re: Function Generator Simulation (Need Help)
« Reply #21 on: February 16, 2012, 04:10:28 PM »
thankyou audio guru....I have made a power supply using LM723.....I am a beginner right now...thats why I made this simple power supply and working fine for me...

Some pics of my power supply Is here :

and finally Circuit Diagram :

Hows Its

#### audioguru

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##### Re: Function Generator Simulation (Need Help)
« Reply #22 on: February 16, 2012, 08:16:09 PM »
What a mess!

#### xsumirx

• Newbie
• Posts: 21
##### Re: Function Generator Simulation (Need Help)
« Reply #23 on: February 17, 2012, 01:01:39 PM »
What a mess!

I know it Looks dirty and even it can let anyone in confusion.........

I can Understand...Ok anyway ....Its all just because it was my first time when I made a PSU indivisiually....

#### Hero999

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##### Re: Function Generator Simulation (Need Help)
« Reply #24 on: February 17, 2012, 05:43:52 PM »
Why bother making your own power supply if you do it badly? You can probably get a crappy cheap Chinese power supply off ebay for much less than it cost for all of the parts and it'll be much more reliable too.

You'll be lucky if it doesn't catch fire or electrocute you.

#### xsumirx

• Newbie
• Posts: 21
##### Re: Function Generator Simulation (Need Help)
« Reply #25 on: February 19, 2012, 06:52:55 AM »
Why bother making your own power supply if you do it badly? You can probably get a crappy cheap Chinese power supply off ebay for much less than it cost for all of the parts and it'll be much more reliable too.

You'll be lucky if it doesn't catch fire or electrocute you.

Don't Think Like a little baby ....Hero
I have tested it upto 4 hour of continuous in ON condition with a 500ohm of Load resistance.

Its was working fine for me
I am just using 1 amp of transformaer....but I can Handle upto 20A of current and 1 amp is nothing as compare to 20A.

Thats why Its will never catches fire at 1A

Its Just Looking like mess but I have made some fan funcation also to keep the heat sink cool.

I didn't go for ebay shop because I have to submit this project in my college as my Peoject......

I had to made this project with my hand...thats why I did not go for ebay shop.

anyway Thanks for suggestion..... !!!!

#### Hero999

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• Electronics God
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##### Re: Function Generator Simulation (Need Help)
« Reply #26 on: February 19, 2012, 02:05:09 PM »
If you expect good marks then you should build it properly. I recommend calling this the first prototype then building it again more neatly.

It's not just a fire risk but a shock hazard too. The cables are so poorly soldered a live mains wire could easily break off and touch the case causing it to float at mains potential.

Where's the mains earth connection?

If you've not got one it's doubly dangerous and if you have then it could easily break off.

Both parts of the case should be connected to mains earth/ground with a longer wire than the live and neutral so it's the last to break if the mains cable is pulled out.

Where's the mains fuse?

Fine, it hopefully won't catch fire if it's working properly but what if there's a short circuit? The wires could heat up, causing smoke and fire. This is much more likely to happen as you've constructed it so poorly.

There should be a mains fuse on the primary of the transformer and it's also a good idea to put one on the secondary side too. Then if there's a short circuit it won't catch fire. In this case the fuse should be slow blow and 1.5 times the fully loaded current taken by the transformer.

#### xsumirx

• Newbie
• Posts: 21
##### Re: Function Generator Simulation (Need Help)
« Reply #27 on: February 19, 2012, 02:19:23 PM »
If you expect good marks then you should build it properly. I recommend calling this the first prototype then building it again more neatly.

It's not just a fire risk but a shock hazard too. The cables are so poorly soldered a live mains wire could easily break off and touch the case causing it to float at mains potential.

Where's the mains earth connection?

If you've not got one it's doubly dangerous and if you have then it could easily break off.

Both parts of the case should be connected to mains earth/ground with a longer wire than the live and neutral so it's the last to break if the mains cable is pulled out.

Where's the mains fuse?

Fine, it hopefully won't catch fire if it's working properly but what if there's a short circuit? The wires could heat up, causing smoke and fire. This is much more likely to happen as you've constructed it so poorly.

There should be a mains fuse on the primary of the transformer and it's also a good idea to put one on the secondary side too. Then if there's a short circuit it won't catch fire. In this case the fuse should be slow blow and 1.5 times the fully loaded current taken by the transformer.

Thanks Buddy.....For your Great suggestion, So, I will really work on your advice about power wiring + primary as well as secondary fuse + make the PCB more Neat and this time I gonna design it with a big chassis as it now....

Thanks buddy...again for your Great advice......