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DC negative Output

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DC negative Output

Postby ciacco85 » Mon Dec 19, 2011 11:22 am

Hi
About the ADC24 PCB full of holes and port provided with the data logger itself.
I want the +5V and -5V to bias some OpAmp used as Instrumental Amplifier but only the +5V and +2.5V works/are connected to the Data Logger.
Tester says that -5V port is grounded, but i'm sure there's this voltage somewhere in the PCB because the are a lot of holes in the PCB where it's written 5V, -5V or AG and the Voltage match (unless with some error +5V->5.3, -5V->-7V)
I don't want weld anything in the PCB, becouse i want to weld only in a matrix board, so?? How should i pick the -5V?

Now i'm developing a prototype with a bread board, but the next step is to eliminate the PCB and connect the ADC24 with my own circuit with "25 poles dsub" port. Where are some information about the pins? I need to know what analog/digital-input/output channel is every single pin

PS: In all the datasheet/help it's not even written a word aboud DC output!!!!!
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Re: DC negative Output

Postby Pico Stuart » Tue Dec 20, 2011 9:06 am

Hi there,

Thankyou for your inquiry with regard to the ADC-24 data logger and associated rails. You can plug the Terminal Board directly into the analog connector on the ADC-20 and ADC-24 Data Loggers. Alternatively, you can use a standard 25-way male-D to female-D parallel cable to connect the Terminal Board to the Data Logger.

The power outputs are as follows:-

+5 V ±1.0 V @ 2 mA
-5 V ±1.5 V @ 2 mA

Please see table below

ADC-24.png


In addition to this please find link below to the ADC-20/24 user guides and terminal board application explanations on taking measurements, voltage divider connections, and measuring current. There are also examples of pratical applications such as measuring Light level, ph, temperature including a thermocouple application.

http://www.picotech.com/document/brochures.html?id=44

http://www.picotech.com/document/pdf/adc2024_terminal_board_user_guide-5.pdf

http://www.picotech.com/document/pdf/adc20.en-3.pdf

if you need any further assistance you can also contact me via support@picotech.com

Kindest regards,

Stuart
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Re: DC negative Output

Postby ciacco85 » Tue Dec 20, 2011 10:23 am

Datalogger datasheet:
+5 V ±1,0 V a 2 mA
-5 V ±1,5 V a 2 m

Sensor (INA 129) datasheet :
POWER SUPPLY: typ ±700 max ±750 µA (between ±2.2V to±18V)

No problem for voltage, but if I've 8 sensor that need this current
I don't undestand what is the max number of sensor

2/0.7 = ~2 (same as 4/1.4)
2/1.4 = ~1
4/0.7 = ~5
Can the Datalogger supplies more current if i connect it with the typical USB cable for external HD? The cable that supply 5V and 1A with 2 parallel head connector and 1 female connector.
Maybe I've given an idea for your future relase because I can't understand how you have developed this device with only 0.5mA
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Re: DC negative Output

Postby Pico Stuart » Fri Dec 23, 2011 11:03 am

Hi there,

Thank you for your observations with regard to the ADC-24. Further to your inquiry with regard to the 2ma of current provided as an additional feature of the ADC 24.

The ADC-24 has been designed with the following in mind. The ADC-20 and ADC-24 High-Resolution Data Loggers offer the ultimate in precise and accurate readings. Features such as true differential inputs, galvanic isolation and software-selectable sample rates all contribute to a superior noise-free resolution.
The ADC-20 is equipped with a 20-bit A/D converter, and can maintain a gain error of 0.2%. The four true differential inputs may be configured as eight single-ended inputs or any combination in between, such as two differential and four single-ended. The ADC-24 is equipped with a 24-bit A/D converter, and can maintain a gain error of 0.1%. The eight true differential inputs may be configured as 16 single-ended inputs or any combination in between. Power and connection to a PC or laptop is through a USB 1.1 or USB 2.0 port. Using the supplied PicoLog software, you can record,
monitor and analyse collected data.

In essence you would need an independent power supply. This would be the preferred methodology and you will not be able to increase the current giving capacity as the logger was never designed to accommodate the functionality of being a power supply for multiple sensors.

It would be better to use a dedicated power supply in this instance.

If you require further assistance please do not hesitate via support@picotech.com

Also I wish you a very merry Christmas,

Kindest regards,

Stuart
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