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  1. C

    Nyquist and data logging

    First of all, thanks a lot for your reply! A lot of info and incredibly helpful. My application has a fixed structure in the seabed, this structure then has a supporting arm which protrudes out of the side and can flex in the waves. I have a load measuring device in the moving arm, which...
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    Nyquist and data logging

    Hi, I'm not sure if this is the correct forum, but couldn't see where else to post. I'm looking at a datalogging application where I am measuring the force acting upon something due to sea waves. Due to the mechanical setup, my numbers will only be positive. I am trying to research optimum...
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    Optical Bonding Issues using UV agent

    Hi, I have a product which is essentially a handheld device with a small screen in, to be exact... a LS027B7DH01 Sharp 2.7” 400 x 240 Transflective LCD. This is then bonded to a clear plastic window using Novachem Optimax 6435 adhesive. The adhesive is cured using a UV light, a high power...
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    Best place to buy used electronics?

    Hi, Can anyone recommend a good place to buy used electronics equipment such as power supplies? Specifically I am after a dual quadrant power supply for testing of electronic charging circuits in our device. The cheapest one I can find brand new is the Rohde & Schwarz HM8143 on RS...
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    CO2 cannister valve

    Hi, I am working on a project where I need to activate CO2 coming out of a small canister, like this, does anybody know of a valve which could be used and electrically activated? thanks,
  6. C

    4-20mA splitter

    @Alec_t I noticed whilst soldering some parts on my circuit that when turning the soldering iron on/off there seemed to be some interference with the circuit. I have added a 100mH inductor in series with the input in loop 1 and a 100uF capacitor with one leg between the inductor and the input...
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    4-20mA splitter

    @Alec_t I have now rebuilt my circuit, before I was using SMD components and the LM358N soldering them onto a dev. board. I have rebuilt the circuit using through hole components (a couple of OPA347PA and 2N222A BJTs) on a bread board and I am now getting the desired outcome. thanks for your...
  8. C

    4-20mA splitter

    @Alec_t with the IA disconnected from the splitter circuit entirely, and putting a 100R resistor the output reads 0.4V. thanks
  9. C

    4-20mA splitter

    @Alec_t I have replaced R1 for a 100Ohm pot which is set at 50%. R1 and R2 are 50Ohm. Very confused! :mad:
  10. C

    4-20mA splitter

    @Alec_t No I cannot measure any current flowing through R1 and there is no voltage present at pin 3. I have also tried a mA injector but this signals a loop error when I connect it. The mA injector was connected such that the mA output replaces I1 in your circuit, and the common is...
  11. C

    4-20mA splitter

    @Alec_t Thanks for the circuit - I have managed to get it working on multisim but not in real life! I have built the circuit up with only the first amplifier in use, I will add the second one afterwards. I believe the problem I am having is that my 4mA input to the non-inverting A input is not...
  12. C

    Battery life calculation.

    Thanks - yep I will factor in more capacity for temperature effects etc. but I just wanted to check my initial calculation was correct. thanks
  13. C

    Battery life calculation.

    Hi, Please can someone help me with calculating how much battery capacity I need. Calculating different ways which all seem logical in some respects, I can get very different answers! What I have is: - A datalogger which takes a sample 3 times a minute. - The sample time is ~1sec and draws...
  14. C

    4-20mA splitter

    They will share the same 24V Thanks
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    4-20mA splitter

    Hi, I need to make a simple 4-20mA splitter to mount on a small PCB. It needs to accept a 4-20mA input, and then provide 2x 4-20mA outputs which are a mimic of the input. I have a 24VDC power supply and no current limitations. The logic to me seems like I would need to amplify my current...
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    R/2R resistor ladder

    This is my attempt at 3 Firstly working out for A = 0, B = 1 and C = 0 working from point E, if B is high then the voltage passes through a 2R/R potential divider producing an output of 1/3 of VIN. This then in turn passes through a potential divider of 2R/2R and becomes 1/6 VIN (1/3 x 1/2)...
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    R/2R resistor ladder

    Ok so I think I understand what you are saying. this is my attempt for explaining 1: Working from point A, when A is high the voltage passes through a 2R/2R potential divider and becomes ½ of VIN at point F. The voltage then continues through a 2R/R potential divider and is further divided...
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    R/2R resistor ladder

    Hi, I have a question in my HND about R/2R ladders, I have been given the diagram below and asked the following question: The diagram of FIGURE 1 shows a 3 input R/2R digital to analogue converter circuit. By working back from the output (or otherwise) to find the equivalent input resistance...
  19. C

    Boolean Logic check

    just noticed I have my inverter on the B input on the first half of circuit 2, should be on the A. Will change this.
  20. C

    Boolean Logic check

    Hi, Could somebody please confirm for me that I have my assignment answers correct? The boolean expression is at the right hand side at the final gate. Thanks thanks
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