Re: International standards

one

Sorry, that should be "pin 14", not "pin 8".

I'm guessing that the resistor should be between pin 14 and pin 6, since connecting 14(Vcc) to 7(GND) with the resistor seems pointless.

I need to read a 12v pulse from a serial port, Can I connect that 12V pulse directly to the serial cable (Receive pin) and get information from there?

sorry for the delay, im not sure why the capacitor made your mosfet die, but isnt the mosfet going to be running a bit close to its specs? if the mosfet is dieng it seems that the mosfet is not capable of diming the lamps as it gets too hot or exceeds its safe operating area. what power is it going to disipate when its half on ?

just thought is your rectified 38vac smotthed? if not it might explain the destruction, you wld need to put in a gate protection diode with anode to gnd and cathode to gate, u cld use a 12v zener to give even beter protection, this wld stop the negative transients on the supply cuasing the gate to be driven far too negative by the capacitance, this might be a good idea anyway.

the mosfet has an inherent parasitic capacitor from its gate to drain anyway, but this is usualy in the order of tens or hundreds of picofarads. usualy its responsible for slow turn off times but this is what u actualy want anyway.

Colin =^.^=

but

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actualy if its unsmothed rectified ac then the miller cap wont work anyway. instead you cld try puting a source resistor so that the curent varies more slowly with respect to the changing gate voltage. i not read all the other replies yet maybe youve fixed it already tho ..

Colin =^.^=

Does a dryer motor have a starting capacitor? That's what I'd look for.

John

the idea of using the miller efect is that the gate voltage varies only very slightly from full on to full off, and the point at wich it does this can vary a lot, so any capacitor from gate to ground is going to have much more efect on turn on time than fade time.

a much smaller capacitor from gate to drain will not have much efect while the device is fully on or fully off so wil not impose much delay, but as soon as the the drain voltage rises the capacitor wil charge up and this charge curent wil rob the gate of its drive stoping it from rising as fast, thus the rise time of the drain voltage is limited to the suplied gate current. dv/dt = I/c.

sorry it seems u have problems with it, see my other posts too, this thread seems to be totaly screwed up on my news server for some reason, 100s of duplicates that all arive many days late, and all disconected.

Colin =^.^=

That doesn't sit well Terry..... the volume allowed for the primary winding is the most valuable real estate on the bobbin. Having primary windings that do nothing doesn't sound right.

Is that how they are marked, or could there be some combination of windings that allow those idlers to be used?

I need URL of any educational website that features

1. Basic AND OR , etc. gates in electrical schematics as well as in symbolic, combinational and sequential design theorem.

1. Microprocessor-based design.

2. Memory Controller design.

1. DRAM / other types of memory chips: descriptions/ design methods.

Going to job interview, and want to review stuff.

Hi, I am working on a logic board that uses resistor packs. I'd like to know what they are without having to desolder them out. One is 10A102G. I assume this is a 10 pin 1K bussed type, A standing for bussed. The other is 8B331G. I am thinking 8 pin 330R isolated type, B standing for isolated. I really need to know if I am right on bussed and isolated. Hope someone can help me. Maybe there is a place on the internet to tell me that but I have been unable to find any info. Thanks. Jay

These numbers indirectly tell you the internal resistance of the supply. It's the slope of the graph, of course. Use that to figure out the dissipation at various current levels for both of these windings, add them up, and decide how much you want the transformer to dissipate.

Or, just put a load on it and watch the temp. rise. I think one of the gurus beat me to this one, however.

Have Fun! Rich

----- 47.0, which is pretty flippin' close to 46.9. I'd say, put the two small ones in series, and that string in parallel with the other one.

Maybe for a first smoke test, put a, say, .1R resistor in series with each to see how well they current-share.

Have Fun! Rich

It _could_ be, but it could also be any number of other things. You haven't shown any component values here. Do you even have a meter? Is the mic known good? Have you double-checked all your connections?

We need much more to go on here.

Good Luck, Rich

I'm getting ready to order some capacitors in the range of 1pF to 1uF and see that both regular ceramic and monolithic ceramic capacitors are available in the same capacitance, voltage, temp coefficient, price range. What's the difference in a regular ceramic and monolithic ceramic capacitor? Why would you use one over the other? Thanks. ______________________________________________________________________

GRAVITY:

It's not just a good idea-IT'S THE LAW!

what kind of power converter would i need to connect 3 of these laser pointers to a 110 volt wall outlet?

I've been testing the watering circuit i built:

It was working OK with an LED in place of the coil, and a 10 uF capacitor instead of the 1000 uF one. I've just finished building the MOSFET switch part of the system, which works OK by itself.

I just tried testing it with the coil and the 1000uF capacitor, and now the 4538 is not working right and getting very hot when I switch the power on. Switching it off and leaving it doesn't fix the problem. Could this be a case of SCR latchup failure? The only way I can see that this could be happening is if the fully charged 1000uF capacitor is discharging through the 4538's A1 and B2 inputs. Is this likely to be the problem?

after switching off, i mean. the main symptom apart from overheating is the 393 can't pull down the A1 and B2 inputs of the 4538 any more - it goes down to 10.63V and no further. With the 4538 disconnected, it works fine, switching between 0V and +12V.

The input to an RS232 serial port is supposed to swing between +12V and -12V. A signal between +3 and -3 is undefined.

You can use a 1488 or one of the Maxim ICs to create the correct bipolar signal from your source.

You can also use a 4050 hex buffer for level shifting. Its inputs can withstand a 12 volt input when its supply is 5 volts. The output would then be capable of being read by the parallel port rather than the serial port.

See here: