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  1. (*steve*)

    Making a variable power supply variable... (what?)

    The maximum output of the dac is less than the maximum output voltage I want.
  2. (*steve*)

    Making a variable power supply variable... (what?)

    Just in case you're wondering how the circuit is reverse engineered... I used a magnifying headset, a multimeter, some datasheets, and good old pencil and paper to mark out all the components and the connections between them. With all of those I end up with something like this: And from...
  3. (*steve*)

    Making a variable power supply variable... (what?)

    For some amusement I reverse engineered the buck regulator I purchased from eBay. It looks like this: It cost me about $8 and claims to be 10A rated. The chip itself is rated for 8A, so that's a bit ambitious. I only expect a couple of amps, so it should be fine. And the schematic looks...
  4. (*steve*)

    Woke up this morning

    It was soooo close to being a blue blood moon!
  5. (*steve*)

    Making a variable power supply variable... (what?)

    So I guess you'd recommend this: Should I add some resistance between the d2a and the op-amp? If so, what sort of relationship should there be between the RC time constant and the switching frequency?
  6. (*steve*)

    Is the following a universal gate?

    By wiring it as an inverter. It's trivial. Tie one input to logic 0 and the other input will cause the output to be inverted. I will leave it up to you to determine which input is which.
  7. (*steve*)

    Woke up this morning

    And look what I saw. It was a bit cloudy.
  8. (*steve*)

    Is the following a universal gate?

    I'm not so sure...
  9. (*steve*)

    Is the following a universal gate?

    If you know of another universal gate, and if you can make it using a combination of these, then this must also be a universal gate. The things which may lead you on your way are finding a way to implement an inverter, and a simple (perhaps visual) understanding of Demorgan's laws.
  10. (*steve*)

    Making a variable power supply variable... (what?)

    I'm just cautious about adding additional gain to a feedback circuit that already has a lot of gain.
  11. (*steve*)

    Hello, can somebody help wich transistor is like bfg520

    Is this oscillator working up to the GHz range? The ft (Transition Frequency) of this transistor is 9GHz. if an ft of 6GHz is OK, then you could try this. The package is different so you'll have to do a bit of redesign of the board. There are others at Digikey. Other suppliers may have...
  12. (*steve*)

    Making a variable power supply variable... (what?)

    OK, weird title. What I want to do is to make a variable power supply controllable by a microcontroller. This is a switching (DC-DC) power supply, and the generic circuit is as follows: See the datasheet here. The Adj pin feeds into a comparator which compares the voltage on this pin to...
  13. (*steve*)

    Missing Edit & Cancel Options on Posts

    @Ian would be the one to know if anything has changed. As moderators, we don't get timed out of editing and wouldn't notice if there's been a change. In this sense we can only rely on what other members are saying. I'm pretty sure the timeout was significantly longer than just 1 minute.
  14. (*steve*)

    Missing Edit & Cancel Options on Posts

    PM me with a description of what you want to edit and I'll do it for you.
  15. (*steve*)

    Vacation

    Good. Because apparently what's lost in Vegas stays in Vegas too. :-)
  16. (*steve*)

    Cannot connect to my router

    It's a bit suspicious if the 3.3V pin reads 0V though. This may be by design, or it may indicate a problem. Perhaps on the other forum you can enquire if this is expected.
  17. (*steve*)

    Comedy Thread

    I, for one, welcome our universe creating cephalopod overlords.
  18. (*steve*)

    Basic understanding of low pass filter

    What you're describing here is the "step response". Adding a DC signal involves a higher frequency component (the change in voltage). There are mathematical relationships between capacitance, current, and voltage (as there are with resistance, current and voltage). In the case of capacitance...
  19. (*steve*)

    Questions about chargers & charging a 2kWh section of a Chevrolet Volt battery

    3P12S literally means 3 in Parallel, 12 in Series. Normally, a charger for a pack like this will connect to each end of the battery, and in addition will connect between each set of series elements so it can ensure none get overcharged. While discharging it can monitor these to indicate when...
  20. (*steve*)

    Basic understanding of low pass filter

    Think of a capacitor as being a type of resistor for AC signals. It differs from real resistors by having a property like resistance which changes with frequency. The higher the frequency the lower th is value has. This thing like resistance is called reactance. Many high pass and low pass...
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