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VolkanG
Joined: 05 Feb 2003
Posts: 2
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 05 Feb 2003 18:27 24 OUTPUT SELECTION WITH 9 SWITCH. |
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24 OUTPUT SELECTION WITH 9 SWITCH.
I will have 24 different output voltage levels changes between 16 Vdc to 60 Vdc 20 mA. I will select these outputs with 9 different switches.
It would be very helpful any suggestion or idea.
Thank you for all. 
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flatulent
Joined: 19 Jul 2002
Posts: 4856
Helped: 292
Location: Middle Earth
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| 05 Feb 2003 18:30 DAC |
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| You can make a DAC with an op amp that has the voltage and current rating you need on the output. You then put a set of resistors and switches in series to connect the summing point to a fixed reference. The resistors are binary weighted. There is one resistor always connected to set your minimum level. This way you will only need five switches.
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VolkanG
Joined: 05 Feb 2003
Posts: 2
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| 05 Feb 2003 18:42 |
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Hello,
I will check the dac and opamps today.
In my little project user will use always these 9 switches like that first switch group will push the user to select one of these 3D, 4D, 5D
second switch group will push the user to select one of these 8Kv- 14Kv- 16Kv and so on totally there will be 9 switch and operator will use these switches to change the voltage levels which will be applied on input of other circuit.
Now I will change the input voltage of this circuit by potmeter but I will 24 different voltage level and I want to make this process automatic and more safe. Operator will not change the voltage levels which will predefined by the circuit before. Only I will give some tolerances
Thank you for your help 
3D - 4D -5D / 8Kv- 14Kv- 16Kv / F- T - P
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qaz
Joined: 31 May 2001
Posts: 14
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| 08 Feb 2003 2:35 |
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I suppose the 24 outputs are not evenly distributed and the 9 are toggle switches.
1. Tie the 9 switches to the address input of a table look-up EPROM
2. Feed the binary-weighted outputs of the EPROM to a DAC
3. Connect the output of the DAC to a LM324 Op amp and a couple of transistors to boost the output to 16~60V.
Done.
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