MP

I have never been asked to pay postage on samples. Not from National Semi or any of the other manufacturers. However, I have a business. Perhaps you tried to get samples as an individual or student? MP

If you mean to convert the current on your present system to a voltage, the simplest way to do so is to drop the current across a load resistor and measure the voltage. If you mean is there an easier way to get a 0 to 12.5V output from a 0 to 900 ohms resistance, I am not aware of anything simpler than using an op-amp. MP

I must not be understanding what you want because it sounds too easy. Why not an op-amp with your variable 0 to 900 ohms in the feedback loop to give you 0 to 12.5V? If this is not it, maybe you should show what you already have and explain what you want to be different. A drawing works really well. MP

You should be able to figure this from the X and Y coordinates to the left of the code input window which is located above the schematic window. I do not know of a way to just type in the coordinates. MP

Price? MP

Please post a price. MP

Wouldn't that calculate to about $35 for the board and $100 for the UPS International Priority shipping? MP

Will this help? It has some Excel spreadsheets that show some of the formulas. http://ece-www.colorado.edu/~bart/book/book/chapter7/ch7_3.htm#top MP

To change the board size, you just click on the corner of the board outline and move it to the size you want. However, if you have the free version, you will only be able to put your parts inside the size contraints allowed by the program. The reason you do not have VCC and GND connections is because you have not selected supply pins from one of the supply libraries. You choose a symbol for VCC and one for Ground, then connect these to the appropriate pins of the components. If you ran an ERC, it should have told you it was missing these connections. Also, you can select a solder pad from the solpad library to have a pad that you can connect the power lines to. For example: Once you connect a GND symbol to a Ground solder pad, you will see an air wire on your board layout going from the GND pin of the IC to the solder pad. MP

I think I know what you want to do, now. If you can program a micro, you could connect a port line to the phone line through an appropriate transformer and have it listen for the high pitched tone after it gets the ring signal and produces an off-hook voltage on the line. Obviously, there will be no high pitch in a voice call. If it gets the high pitch, turn on the relay for the fax line. The fax will miss the first handshake, but the fax will always repeat the handshake if it does not get a response. After a very short time-out, if the micro does not hear the tone, then relay to the voice line. You will need to also figure out some routine to reset the micro back to a listening stage again. Perhaps with a little more code to determine when the phone is no longer in the off-hook mode. Does this sound like what you are trying to accomplish? MP

You might try www.earthlcd.com to see if there is a similar model there. They usually have links with data sheets and pinouts. MP

You could use the UCN5804 outputs to turn on and off power transistors, but then you could also do this without even using the UCN5804 chip. It would be hard to relate the rating to oz/in. since the current ratings of the motors are what you actually calculate. Different gear ratios, etc. would give you different results. MP

No one has a forum like e_lab 8) MP

You might be able to match it up at www.earthlcd.com Perhaps they have an equivalent or one which looks the same. MP

Yeah, like I said, you could just build your own system. These expensive ones pull the air through a HEPA filter which is pretty expensive in itself. Unless you do a lot of soldering, I would not worry too much about it. A small DC fan to move the fumes away from your face would be a plus. MP

You could probably make something on your own, but here is the Airex model that is sold with Weller soldering stations: https://www.galco.com/comp/SA011599.pdf MP

RP1 is pulling it to logic high through a resistor. Leaving it open is essentailly a high. You only need to connect a switch to ground if you ever want to pull it low. MP

Cooperman, I do not think the "High Voltage" members need to worry much, unless they are making their own vacuum tubes. According to the 4 requirements in your link for a device to be emitting radiation, requirement #4 is "Low gas pressure between cathode and anode, i.e., a moderately good vacuum." MP

Only_, LINE IN is where your device is accepting or acquiring the audio signal from another source or device. LINE OUT is where your device is sending it's signal to another device. Hope that clears it up for you. MP

Inverters usually make a signal by switching the full potential voltage on and off with a transistor and feeding this directly into the transformer to limit the current loss. Your DC-DC converter would lose current in the conversion process, then would still have to incorporate the same charge pump circuit as an inverter to generate an AC waveform. I think you would not only have a circuit with less current, but would require more parts in doing so. MP

This refers to the current flow in the windings of the motor. If you ground this pin, then the motors will be turned OFF. This option is available so that you can connect a safety switch if needed. MP

Your relay is made by Panasonic. It is a 12 VDC / 5A relay. Here is a link to the data sheet that will help you understand the markings on the case and what they mean. http://www.alliedelec.com/Images/Products/Datasheets/BM/AROMAT/Aromat_Industrial-Control_7881012.pdf MP

You do not want to breath the fumes from the flux. Yes, it is considered a carcinogenic. You can find this information in the Material Safety Data Sheet (MSDS). All manufacturers must provide an MSDS sheet if you ask for it. Here is the MSDS link to one brand of flux: http://www.ee.ryerson.ca:8080/~jkoch/MSDS_Sheets/MG_MSDS_835-liquid.htm Here is another: http://householdproducts.nlm.nih.gov/cgi-bin/household/brands?tbl=brands&id=18018039 Take care when soldering. Use a bench mount fan that will pull the fumes through a filter if you have this available to you. MP

The fax tone is only the handshaking signal. None of your fax message is on this tone. After this signal is transmitted and both devices have told each other they are connect through these tones, the data is sent. This data is sent on the same line as your voice, so there is quite a bit more to this than just isolating the fax tone to another line. You will need some type of smart circuit to make this happen. A few discrete components will not do it. MP

What is the brand and model number? Are there markings on the device to indicate this? MP