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  • Users: hrc
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  1. hrc

    electric door solenoid

    I'm going to cross post this in several groups...so I aplogize in advance but it does cover several areas. I am searching for a source that can provide a door lock solenoid, but its a little different (maybe?) than the normal one. I need the ability to use a key to unlock it normally, but on a...
  2. hrc

    capacative sensing

    posting for another engineer who is looking for techincal information on how capacative sensors work. Links to discussions, white papers or sites. Thanks
  3. hrc

    Remind me...current flow on single ended 3 phase loads

    I am pretty sure we discussed this before....but I was trying to run thru my notes and did a search but didnt find what I was looking for. Given a 208wye system, leg to leg connections to a load (single phase load). Each load draws 14A. So, if I have 3 loads, balanced across the legs...
  4. hrc

    Design guides for Class I Division I

    Looking at doing a design of a controller board that is going to need a Class I Division I certification. Anyone know of basic guidelines on designing equipment for these applications?
  5. hrc

    Looking for an OEM phone module

    Yet another strange request (guess thats why consultants get all the strange ideas thrown at them). Client is interested in a project, where one piece of it is a good old telephone. Not a modem, but to have a micro dial a number and then the user picks up a handset and talks. I've been...
  6. hrc

    Looking for a LCD graphics touchscreen

    Looking for a source for a high res monochrome LCD touchscreen, something around 4"x5", and low cost. This will be driven from a microcontroller so serial interface would be nice but no particulars. I can't use a surplus unit, since this is for a potential high volume application.
  7. hrc

    EU power - standardized 3 phase?

    I've been told...still looking to confirm, that the EU countries have standardized to 415VAC 3 phase (for medium/high voltage). Anyone know if thats true? Seems to me...thats a bigger problem than just changing currancy, having to redo a power grid. Specifics are for England and Germany right...
  8. hrc

    CDMA vs GPRS

    Can anyone explain the difference between using CDMA (verizon based i think) and GPRS (cingular/ATT based)? Is one better than another both in preformance and overall cost?
  9. hrc

    DC current - does it travel inside the wire or just on the outside?

    I know for AC, the push-pull forces the electrons to the outside of the wire (skin effect) but for DC, in a solid wire, does it only travel on the outside of the wire, or will it 'fill' the wire. The background of the question is, a busbar attached to a PCB, where a stud ties it to the "pad"...
  10. hrc

    Isolated 3.3V to 5V 100mA design

    Making a boost circuit is easy....making it 1500V isolated is a little more tricky. Anyone have a favorite circuit they have used?
  11. hrc

    OEM CDMA modules

    I'm looking for a CDMA module that can be incorperated into a design. Presently have a complete packaged device, but the cost is $400, so I'd like to find something smaller and cheapter. The size of this unit is about that of the old style telco desktop modems. It also needs to be a type...
  12. hrc

    4-20mA to voltage

    OK...embarking on something new here. Figure industrial control guys would know better than the circuit engineering but I figure its a toss up. I have several 4-20mA current loop sensors, that I need to read with a micro. First off, for a sensor to be using 4-20mA as its signaling, do you...
  13. hrc

    Rack Mount 3phase transformer to single phase

    I'm looking for a 17" rackmount transformer, around 15kVA. primary is 480VAC 3 phase, need either 240 single phase or just a step down to 208 3 phase wye. Anyone give me some pointers to mfg that make these?
  14. hrc

    gasoline fumes sensor

    I'm not sure if this is the correct place to be asking... I'm trying to locate a solid state sensor that can detect gas fumes, such as if they become too concentrated, something like a CO detector. I'd prefer a sealed sensor to eliminate having to put the signals thru an intrinsic barrier...
  15. hrc

    Same power source, two feeds, common connection

    OK...picture this. Two 3phase 208Y w/neutral into a box, from the same load center. Picking off a phase and neutral from each to get 120VAC. Open frame AC/DC power supply, powered from the 120VAC. Typically both power cables are active, so just picking one of them to provide power to the DC...
  16. hrc

    Splitting up wiring to smaller guages

    Feeding into a control box with a 208Y feed, using 6/5 SO cable, full load on the system is 43.846A/phase [derived from having a power supply with a draw of 14.42A, so using two legs and three supplies split across, each phase will see a draw of 28.8A, and then a 15A single phase 120V load for...
  17. hrc

    SHT71 temp/humidity sensor - accuracy issues

    I'm working on a project where I have a Sensirion SHT71 device tied to a PIC micro. www.sensirion.com/en/sensors/humidity/sensors_devices/sensorSHT71.htm I'm quite sure the code is working, thats not the issue at hand. If it wasn't then I wouldnt be getting semi valid, or sometimes valid...
  18. hrc

    Ampacity of SO cable (vs single wire in air)

    Looking at the standard tables in my uglies.... #8 in free air is good to 60A #8 in a raceway is good to 40A (3 conductors in raceway) What about SO cable? I know that the reasoning for the derating in the raceway, so is SO under the same consideration because the conductors are bundled up...
  19. hrc

    Transfomer on a speed controller output

    Just was thinking...I saw where a 230 3phase motor was being driven from a AB speed controller, but attached to the motor wiring (via a jbox) was a transformer to run an exhaust fan. I asked the guy putting it in, he shrugged and said it was how it was designed but I wonder how the transformer...
  20. hrc

    ZigBee users/experts

    Anyone out here familiar with ZigBee Yes...I know the basics (802.15.4) and what it does, etc Have more questions about the mesh network, the coordinator, the slaves and how they know WHO to talk to...

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