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cyw1984
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Posts posted by cyw1984
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I am used a AD5678 -2 (16 bit
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What is a "schokky"?
This project doesn't use nor need a high-speed, high-leakage Shottky diode for D9. It is an ordinary 1N4148 diode.
Use the same kind of opamp with a high supply voltage rating as U3.
Can't you see the PNG schematic I posted? Download and save the pic and open it in a viewer program. It will be very clear. Here it is as a GIF:
output 0V mean that common pin 3 and short to GOUND??? -
Yes.
I think this will work:
Thanks~~But I need add on a NEW shockky or not??
What NEW Op amp should I add on this circuit??
and pin 3 of U3 and NEW op amp connect to where??? thanks -
Hi Cyw,
The output of U1 is an 11.2V voltage reference, and the pots just divide it down. The voltage range is easy to calculate.
However, the lower end of R17 has the voltage developed across R7 (caused by output current) adding a negative voltage to R17.
To use another control voltage instead of the existing one that is used to control the current, you would need to re-arrange the inputs of U3 and add an inverting opamp stage.
o..I SEE
Firstly, i should remove all the part of U1 (11.2V),Right??
I wolud like to use another control voltage reference (DAC) instead of the existing one that is used to control the current and voltage.
Also...How to re-arrange the inputs of U3 and add an inverting opamp stage.
Can you draw it to me??? Thanks a lot
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hello all
I want to know the voltag range of -
THX~~~But it ;s don't work~~~
someone can help?? -
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Hi Cyw,
Your circuit is correct for a dual-polarity supply having adjustable output voltages from 1.25V to about 27V.
You don't need an input voltage as high as 30V when anything more than 18V will be fine.
You don't need pots to adjust the output voltages when 2.7k (5%) resistors are fine to produce 15.3V outputs. ;D
Thanks a lot~~
I need pots to adjust the output voltage
because it is use for V reference .....
My AD669 DAC Vref is given by this +-10V -
+/-15V power supply using LM317 and LM337 regulator ICs
How to designa +/-15V power supply using LM317 and LM337 regulator ICs.
Thx
The voltage is used to DAC (AD669)
I have try to design the circuit....
Is it Right?? [img width=680 height=453]
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About Visual Basic6 and RS232 ASCII communication
If I want to send the value (ASCII) to 8051 series port
VB block input:
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0.09
0.1
0.11
0.12
0.13
0.14
0.15
0.16
0.17
0.18
.
.
.
.
.
.
.
29.93
29.94
29.95
29.96
29.97
29.98
29.99
30.00
RS232 transmit :
0000
0001
0002
0003
0004
0005
0006
.
.
.
2985
2986
2987
2988
2989
2990
2991
2992
2993
2994
2995
2996
2997
2998
2999
3000
If i want display 0-30 with 0.00 (ACSII).....
How can I write the VB software , It need to write 3000 structure???? -
D to A covertor reference
Any High Precision +-10 V Reference??
AD688 is too expensive...any other cheaper?? -
Revolver, air pistol, shotgun - take your pick. ;D
I'm joking of course, I know English isn't your first language, I'll try to correct your post for you, I think you must've meant:
It might be oscillating, you should attach a 100uf capacitor followed by a 100nf ceramic disc capacitor on the output of the regulator, if this doesn't work then please answer the following questions:
What are you powering this circuit from?
Have you looked at the output on an oscilloscope?
What output voltage are you getting at what input voltage?
Have you checked the output from the DAC?
Vin=40V
I used the power supply to represent DAC -
Hi nearly old man Staigen,
You are absolutely correct! I was way off with my selection of high-value "turn-off" resistors for the output transistors in my "fixed" circuit. I have now chosen lower value resistors based on what is inside a TIP120 darlington.
I used a 1k resistor in series with the collector of the 2N3906 to limit its collector current and dissipation if the project's output is shorted. It will still provide enough drive to the output transistors to blow a fuse if the output is shorted.
I think the circuit can deliver 30V at 1.5A with a 34V supply to protect the 36V max-rated opamp.
It would be fun to try to stop this extremely high gain circuit from oscillating. ;D
Hi Alun and Cyw,
I don't think a single 2N3055 or power Mosfet can dissipate more than about 60W even on a pretty big heatsink. Therefore the max current is only 2A at low output voltages. That's why I proposed using 2 output transistors in our 0V-30V modified project for 3A output, and using 3 output transistors on our modified for 5A project.
I am sorry..i have try this circuit...but i don't know it 's not work..
the output is not linear and the output is disorder
how to shoot it? -
why i can't open the sc,lbr and borad in other PC?? -
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Of course not. The max output voltage will be 3V to 4V lower than its supply voltage.
I don't know what you mean.
You'll have to try different values until its transient response isn't too slow, and that it doesn't oscillate.
I want to common the Opamp VCC and GND to the Vin and GND
how to do that- -sorry fot my poor english -
thanks again
I get a problem here...
If my Vin 30 or 32V..can the output achieve 30V???
how to change the circuit...because I want to common the VCC and GND to supply voltage....
And what values of filter is suitable???
thanks -
audioguru old man,
I have tied your circuit....It has some problem......
It use 15K resistor series as DAC input....
The Vref is not between 0-10V.voltage drop on the resistor
Also....the output is exactly the same of Vin
What is the cause???
I used the LM358 to test (Vin 36V and Gnd it) -
Hi nearly old man Staigen,
You are absolutely correct! I was way off with my selection of high-value "turn-off" resistors for the output transistors in my "fixed" circuit. I have now chosen lower value resistors based on what is inside a TIP120 darlington.
I used a 1k resistor in series with the collector of the 2N3906 to limit its collector current and dissipation if the project's output is shorted. It will still provide enough drive to the output transistors to blow a fuse if the output is shorted.
I think the circuit can deliver 30V at 1.5A with a 34V supply to protect the 36V max-rated opamp.
It would be fun to try to stop this extremely high gain circuit from oscillating. ;D
Hi Alun and Cyw,
I don't think a single 2N3055 or power Mosfet can dissipate more than about 60W even on a pretty big heatsink. Therefore the max current is only 2A at low output voltages. That's why I proposed using 2 output transistors in our 0V-30V modified project for 3A output, and using 3 output transistors on our modified for 5A project.
Thank you for your help....
Can the cirucit deliver 30V at 2A??
On the other hand, I would like to use LM358 for testing, Is it OK??
any op-amp is prefectly on this cirucit??
As I know CA3140 is 4.5MHz, BiMOS Operational Amplifier with MOSFET -
Here's an idea to make the current limit programable.
U3 is a differential amplifier with a gain of R4/R3, this measures the volagate across -
Use a higher voltage IC or a separate power supply for the IC.
Just add a zenner, see attachment.
Why do you need to offfset adjust? Any error in the output can be taken care of with a small trimmer resistor.
You could also power the IC from a zenner diode shunt regulator to get round the voltage problem but this won't work with my MOSFET circuit, however I can solve this problem too.
I chose a MOSFET because it's simpler, will work out cheaper, has a lower drop out voltage (not important here though), will have a lower quesant current and a far better transient response.
Even though you haven't considered limiting the current at this stage it's still very important to know the magnitude, this will give you an idea of the componant ratings the design techniques you should use. By looking at the componats you've used and your origional design I assume you want the output current to be around 10 amps or so, is the correct?
I want the output current to be around 2 to 3 AMPS.....Your 's enclose can the output achieve to 0-30V???
Also Use a higher voltage IC ................which IC should be suitable on it?? And which you used??
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Hey boys, and old man Audioguru
Lets stop a while and think, and dont rush away
There is so much we dont know about this regulator, but there is at least some data given. We know:
The input voltage is 40 Volts
The output voltage: 0 to 30 Volts, depending on Vref
Vref: 0 to 10 Volt from a DAC
Something we dont know, and i belive we must know:
Output current
In some instances the output resistance of the DAC
Something that would be nice to know:
Data about the DAC(not necessarily needed, except above)
The 3140 IC have a max voltage rating of only 36 Volt, so why stress it above that, use an another IC
Audioguru, i have seen a lot of commercially designed circuits with 2N3055, both switched and linear, and the resistor between base and emitter has been in the range of 100 to 220 ohms, dont you think that 10 K is a little bit high? And also the resistor between the 2N3053:s base and the output, its usally betwwen 1 K and 1,5 K? What is the purpose of the 1 K resistor between the base of the 2N3053 and the collector of the 2N3906? And no offset adjust?
Alun, your circuit is a good one, exept that the 3140 IC are not guaranteed for 40 Volts and there is no voltage limit on the MOSFET:s gate! And no offset adjust.
Whats so wrong with the original circuit, exept that it have the wrong IC and no resistors from the base to the emitter on some transistors? It also lack protection for the base on one transistor and it have no offset adjustment! But, it have output short protection, so it is much safer! The shematic is here under:
//Staigen
It is 12BIT DAC 0-10V
also........It about 0-2V
but....current limit I will design later -
Hi Cyw,
You didn't finish your circuit with the important stuff I mentioned, so I added/changed a few things.
About the only thing that remains is adding current limiting or regulation. If you draw too much current or short the output, it will blow-up! ;D
Thanks a lot...But I have few question about this....
1. DC sypply voltage only 36V, Is ir really suitable???
2. How to caculate the resistor values (10K) between PNP Base and Emitter and NPN base to output(10K and 100K)???
3. What is the values of capacitor should I use??
4.I know it haven't current limiting....I just for testing . did you added current limiting on it??
Thanks a lot...Sorry for my trouble and poor english -
What’s the DAC look like? How many bits?
Voice playback
in Electronic Projects Design/Ideas
Posted
Which chip can playback normal voice?
"one" ,"two"...."three"....."nine".."ten"
then can use the mircocontroller to control each one playing back
Thx