Search results

Search Forums New Posts
  1. AnalogKid

    I need Cycle Timer circuit. 1 hour on 1 hour off and continues

    There re a lot of home-type timers as above, and industrial timers such as barn ventilation timers, that are very simple to use and very reliable. If you really want to build something from scratch as a project, we're here to support that. But it is not the most simple or least expensive...
  2. AnalogKid

    Underwater Wireless Communication

    For the pH and temperature sensors, what is the data format (number of bits or bytes per reading), and what is the amount of data per second or per minute you want to communicate? WiFi is overkill for most sensor data, and the very high frequency makes it difficult to use around water. ak
  3. AnalogKid

    Solid State Relay concern

    I'm playing with a lamp dimmer based on power MOSFET's, partly because I have a pile of them left over from something. I thought I had a cool idea until I found patents going back to the eighties. ak
  4. AnalogKid

    Solid State Relay concern

    Or two SCR's. Keeping it to the most common term for the perceived level of the OP. ak
  5. AnalogKid

    Solid State Relay concern

    To expand on that, semiconductors are called semiconductors because they conduct in only 1/2 of the possible directions. Regular old wire in a circuit doesn't know which end is more positive or negative than the other, and doesn't care. Current moves in both directions with equal facility...
  6. AnalogKid

    Alternative for 8 2N3904 transistors in a single chip?

    No, it won't. Harold has only one post in this thread, and he does not say anything about that. Of course, without a schematic it is impossible to say, but IF (note the big IF) you are using the 3904's as saturated switches, the 2803 probably will drop in with zero circuit changes. The higher...
  7. AnalogKid

    Alternative for 8 2N3904 transistors in a single chip?

    ULN2803 has 8 sections. Also, the 2004/2804 have inputs designed for 6 to 15 V and can operate safely at 24 V, if you need that kind of range. ak
  8. AnalogKid

    what am I

    Will you still need me Will you still feed me When I'm sixty-four - Lennon/McCartney Later this year my electronics-for-money career turns 50. ak
  9. AnalogKid

    what am I

    ...need me, feed me...
  10. AnalogKid

    ECG Circuit Problem

    That is a 7805 acting as a rail splitter. If you've ever seen an app note for using a standard positive boost regulator as a power inverter (+5 V in, -5 V out), it's the same trick but without the correct feedback to maintain the pseudo-GND at 50% of total Vout. As the battery discharges, the...
  11. AnalogKid

    what am I

    Kids! <tsk>
  12. AnalogKid

    Create an UP-DOWN pulse from a single UP to DOWN signal

    The 4017 is not bidirectional. ak
  13. AnalogKid

    Rotating motor direction

    He?
  14. AnalogKid

    Rotating motor direction

    1. The motor rotor stops at an arbitrary angle with respect to the stator. 2. The motor stops with an arbitrary magnetic polarity on the rotor because power was removed at an arbitrary phase angle. 3. Power is reapplied at an arbitrary instantaneous positive or negative...
  15. AnalogKid

    Create an UP-DOWN pulse from a single UP to DOWN signal

    Really need to see your schematic to sort out the details, but this should not be too difficult to solve. One thought is to use stages of another 4069, or 40106 or 4093 to make the delay signal. You'll have much more control over logic polarities and you won't have to deal with the 555's...
  16. AnalogKid

    Record player motor voltages

    The motor *might* have been connected to a transformer secondary so that primary taps could be connected for 120 V or 240 V countries and the motor would see a relatively constant 240 V. Old-time version of "universal input". Or, the motor was connected to the output of the power switch along...
  17. AnalogKid

    How to design a Flip Flop using 555 Timer ?

    Maybe because English is his first language. The term "multivibrator" was coined because the inventors of the two-tube circuit knew that a square wave contains multiple harmonic frequencies. https://en.wikipedia.org/wiki/Multivibrator After that, things get a bit fuzzy. Still, I think the...
  18. AnalogKid

    IR Detection Circuit

    In circuit 1, what is the gate voltage? A 2N7000 requires at least 2 V to start to wake up. All IR circuits have trouble with sunlight, which is why all of those IR remote controls send digitally coded IR pulses, something the receiver can differentiate from sunlight, incandescent light bulbs...
  19. AnalogKid

    Make a relay switch? Like a mosfet high amp.

    At 84 A, Vf would be at least 1.5 V based on Digi-Key's inventory, so power dissipation in an SCR would be in the 130 to 200 W range and it would cost $60.. ak
  20. AnalogKid

    Make a relay switch? Like a mosfet high amp.

    At 84 A, the circuit path (battery connectors, power connector, MOSFET, and wire) will dissipate 7 W for every 0.001 ohm if series resistance. The FET mentioned above as an Rds of 0.002 ohm max at Vgs = 4.5 V. Impressive, but that's still 14 W in a TO-220 package. It will survive a few...
View older results
Top