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    MTBF MIL217 Quality

    Hi I'm evaluating the MTBF for a relatively new smd electronic design. It's not something I've really done before myself. So I've been going through the MIL-217 reliability spec, and evaluating some software and online calculators. I thought I'd start with the component 'count' type then...
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    PCB design for ATEX.

    I'm wondering if I can get some help interpreting a part of the ATEX standard (IEC 60079-18)? I am designing a PCB for ATEX certifcation, encapsulated type 'mb'. Under 'minimum distances' (page 23-24) there is a table (5) and diagram (figure 2) of the PCB stack-up. In my case, from...
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    Calculation of Potting compound thermal resistance

    Hi Could someone please help me with a problem. I have a PCB that fits in an ABS box and is to be completely potted, top and bottom. I am investigating device failure modes, as I need to ensure that the outside surface temperature does not reach 135C. I've worked out that one SOT23 device may...
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    VHDL Possible timing problem?

    Hi, I'm relatively new to VHDL and I wonder if someone could have a look through this bit of vhdl code. The FPGA is a A42MX09, the IDE is libero. I have simulated the code, before and after synthesis and it appears fine. Synthesis does not show any errors. Basically it's a serial data stream...
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    Inner layer track distances

    Hi I am working on a PCB which is going to work at 240Vac mains. I am struggling with creepage and clearance distances, so the only answer I can see is to put the mains Live and neutral on inner layers. I have looked at the spec and see that the clearances for an inner layer will be >0.25mm...
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    Solder resist breakdown voltage

    Hi I wonder if someone could help with this question. What is the breakdown voltage of solder resist. I have seen a value of 500V-1000V/mil. So can solder resist be relied on to reduce the track distance between 240V mains live, neutral and earth. If so what would be the minimum track...
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    Cable attenuation / input impedance

    Hi Could someone help me with a problem I am looking into regarding a lossy transmission line (again) I want to manually calculate what the attenuation and output voltage I should expect for an lossy unmatch cable. I have been using Multisim simulate it, (I have attached a screen dump), but I...
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    Sine-wave DC rectifier circuit formula

    Hi, I wonder if someone could tell me if there is a formula I can use to work out what the DC voltage / average voltage will be in the circuit. (A half way rectifier connected to resistor divider, and a smoothing capacitor on the output of a divider) I think I should be able to work it out, or...
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    Manufacturers cable inductance specification.

    Hi I have another simple question, I hope someone might be able to help me with. When cable manufacturers specify the cable inductance per Metre, (specifically for single pair or multi-pair type, i.e NOT coxial) are they generally specifying a complete loop inductance (i.e for 1 pair shorted...
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    Calculating the inductance per metre from the Cable 'L/R ratio'.

    Hi I wonder if someone could answer this question. It's probably quite simple but I just want to check. I am working on send some AC communication signals down long cables. One particular type of cable has a parameters that specifies an 'L/R ratio' (60 uH/ohms) instead of giving a...
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    Standing waves in Long cables and at 100K-200Khz frequencies.

    Hi I wonder if someone could help with a question I have. I am investigating standing waves on signal (100KHz-200Khz) sent over on long cables, over 1km -3Km. Ultimately with a known load and source impedance and the details of the cable, I need to be able to predict what the signal level...
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    4046 FSK demodulation / loop filter design

    Hi I would really appreciate it if someone could help me. (Sort out some confusion :-)) I am intending to use the 74hc4046 to demodulate a FSK signal. The carrier centre frequency is around 165Khz and the deviation is around +/-2.5%. So I am using a frequency offset. (I am not using any...
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    Looking for alternative for the LM1893 FSK Powerline transceiver.

    Hi I am wondering if anyone has come across a device that is similar to the power line transceiver LM1893 / LM2983 from TI which is now absolete. I realise that has been partly answered before. Unfortunately as far as I can see, I can't really use the other devices that were suggested. Most...
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    transmission lossy line for long Cable

    Hi I have a general question about the standard model used for cable lossy transmission lines. I am looking redesigning a product that drives a signals down very long cables, ie could be well over a kilometre and various configurations. (Ultimately this is due to IC obsolecence). The...
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    Flash Memory addressing latch up.

    I hope I have posted this is in the correct forum as I believe it is a hardware problem with a device that I need help with. I am investigating an intermittent problem that has baffled me. The specific device, 28SF040 512K x 8bit flash memory device, is manfactured by SST. Though someone may...

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