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  1. CDRIVE

    Alarm reset timer

    My Florida Cracker friend Jessie always says "Damn! Sometimes I'm so smart I can hardly stand myself"!!!! :p Good call Duke! ;) Chris
  2. CDRIVE

    DIY Voltage Meter (multimeter)

    Just remember that you can't use a digital meter (it requires a power source) to check its own battery. This means that you will have two batteries. The one you're measuring and the one that powers the meter. Chris
  3. CDRIVE

    Pulsated LD

    Ah, I got ya now. It was the language barrier.. You speeking English and me speaking Chris-eese! ;) Chris
  4. CDRIVE

    Pulsated LD

    No Kris I caught the fact that the Output pin was sourcing and sinking the RC time constant. I think my sim didn't lie it's just that I didn't set the start & end times with a settling time delay. Tina gives me 3 choices when running a Transient Characteristics.. (1) Find Operating Point (2)...
  5. CDRIVE

    Sensing and measuring current?

    The LT1787 data sheet was very clear and includes typical circuits. They guarantee Vsource lower limit = 2.5V which means it will probably work even lower. Chris
  6. CDRIVE

    Pulsated LD

    Aw shucks I'd have never guessed that! :rolleyes: Somethings still haven't changed. It seems that no matter how many times we ask, beg or threaten,.. the cryptic responses continue! :( I spiced it on my other PC before I posted that. I didn't record the results but I recall Mark being...
  7. CDRIVE

    What value of resistors do I need and a sanity check

    Kris, you've made a wise decision. Chris
  8. CDRIVE

    Low voltage sine wave output

    Why didn't you draw it as Bob did? It would be much, much easier to follow. You're only difference would have been the location of V+ and V-. Putting them in a box to indicate two OpAmps per chip isn't necessary. SOP is to just name them U1A and U1B. ;) Chris
  9. CDRIVE

    Pulsated LD

    The duty cycle of the left hand circuit is not variable. The author says it's 1:1 (50%) but it's not. Only the frequency can be changed by varying the value of R1 or C1. A 555 can be wired for variable duty cycle but not like that. The right hand circuit claims a sine wave output. That's also...
  10. CDRIVE

    What value of resistors do I need and a sanity check

    10mA can be lethal if it's through the heart. I would also bet that it could cause severe brain damage if through the brain. Chris
  11. CDRIVE

    BEAM 1381 solar engine problem

    You seem to have disappeared but while you've been absent the other solar engine thread has been active. https://www.electronicspoint.com/miller-solar-engine-1381-replacement-t262497p3.html The more I read the data sheets for these two chips the more I'm convinced that the 2N3904 isn't...
  12. CDRIVE

    Sensing and measuring current?

    The LT1787 is rated down to Vs = 2.5V. Chris
  13. CDRIVE

    MIller Solar Engine 1381 replacement?

    Steve, I thought so too but neither thread specified the motor current. The manufacturers spec Vgs(Thld) at an extremely low Ids. Chris
  14. CDRIVE

    BT150 Thyristor equivalent(BT151) has just exploded !!!

    You're not the owner? Chris
  15. CDRIVE

    Sensing and measuring current?

    If you use a 100mR current sense resistor in the low supply rail you'll develop a voltage drop between 50mV and 200mV. Feed this into an OpAmp with a gain of 100 and you'll have an output voltage swing of .5V to 2.0V. If you increase the OA gain to 1000 you can drop the sense resistor to 1.0mR...
  16. CDRIVE

    MIller Solar Engine 1381 replacement?

    Steve, at present we have two topics involving the Solar Engine. The other one is using the MN1381 but has issues when driving a heavier load. After comparing both Data Sheets I've concluded that both of them have some parameters that were extremely confusing until I read them repeatedly. Either...
  17. CDRIVE

    NPN circuit not behaving...

    Kris, have you been texting? :p After beating up the new guy I'd be accused of nepotism if I said that was OK. ;) Send it off to the IEEE to see if they'll accept it. Hey, if they say it's OK who am I to argue? Chris PS. Yeh, Darlingtons do take up real estate.
  18. CDRIVE

    NPN circuit not behaving...

    I'm sorry but our industry doesn't accept schematic freestyle. We're not going to let what happened to the English language, do to texting habits, migrate to our field. Besides that point are you aware that a Programmable Unijunction Transistor is drawn very similar to what you drew? Yes...
  19. CDRIVE

    MIller Solar Engine 1381 replacement?

    After comparing the data sheet waveforms between the 1381 and the DS1817 I now see what your problem is. As is (no additional circuitry) the DS1817 will not replace the 1381. There is nothing in your circuit to turn it off after it's triggered. Chris
  20. CDRIVE

    MIller Solar Engine 1381 replacement?

    The 138(n) series come with 1 of 3 output variations. CMOS(Push-Pull), NCHAN(Open Drain) and Inverted CMOS(Push-Pull). The DS1817 is provided with CMOS Push-Pull output only. Typical output current appears to be about 350uA. Is your circuit like this with the PNP eliminated...
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