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    LED transistor relay with adjested delay

    I think something might have been lost in translation. Don't follow the "always on" but, ... not always on. . Maybe you could draw up a table or something (a state machine, if you know what that is) which describes the states that the system can be in; (1) nothing happening nothing on, if "turn...
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    Photodiode falltime problem

    What was the circuit that the PDA10a2 was in? If the scope input is high impedance, then the charge on the diode junction has no path to go anywhere. . I vaguely remember circuits designed to keep the diode voltage at zero to minimse the effects of any junction capacitance. Probably short of...
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    Low-frequency High-amplitude piezo driver using ATTiny 85

    Another reason to consider changing the piezo drive Regarding the mosfet across the capacitor thing. At 10Hz, you would probably saturate the core of the input inductor given that you are effectively shorting it to across the supply. This would mean a high current through battery, inductor...
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    New project

    What's on the other end? As in where's the data going? Embedded board? Desktop PC? to the cloud? . Frequency range? Samples per second? 1Gsample per second or 1 sample per hour? Input voltage range? Range to collection device? Accuracy required? 8 bit? 24 bit? . In through the sound port? ...
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    Variable Frequency Filter Mfg. by A. P. Circuit Corporation AP265-5

    Not quite nothing, Jerry, http://www.searchdatasheet.com/AP6VC-datasheet.html https://www.lintechcomponents.com/product/manufacturer/58390/show
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    Replacing a battery charger transformer with a audio transformer can I do it?

    Just to add to what bertus said. The suggested replacement is probably not sufficient power rating for a battery charger. Battery chargers tend to be required to handle lots of power to charge quickly. Other devices, usually less, so not sources of replacements.
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    8x8x8 led cube

    That instructable has code. :) I'd expect that you'll find code for cubes & probably your cube online, if Bertus's link doesn't lead you to some.
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    Replacing a battery charger transformer with a audio transformer can I do it?

    Short answer: unlikely. Unclear whether you mean a transformer for the input power of a piece of audio equipment or an output transformer intened for the audio signal. But, in general; Transformers change voltage and current into different voltages and current, they trade one for the other...
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    Low-frequency High-amplitude piezo driver using ATTiny 85

    I googled for circuits. I no not always a good way to find typical, but anyway one-sided drive + resistive Similar with inductive component or aim for symmetrical drive?
  10. N

    Low-frequency High-amplitude piezo driver using ATTiny 85

    Can you give the source of the circuit? The placement of the FET relative to the diode is not what I'd expect. Circuit correct? I'd initially expect the diode between the fet and the capacitor, so it doesn't drain the capacitor. As it is, the fets are in parallel. :) . Also shorting the stored...
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    8x8x8 led cube

    Great to hear. The main reason that I tell myself that I have not made any of these is that next step, of having to design those shapes/patterns/dynamics that look pleasing. I love some of the random, yet sort of organic, dynamics things you see on displays. Hope yours goes well. . The current...
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    Audio alarm timer, tantalum value issue help

    Yep. A fun book. Thanks for the reminder. Also good that you had it right, all but one power supply wire. Had a lot of fun with LM380s a while back. I do have a vague memory of them getting hot at times, but maybe I mistreated some.
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    555 astable

    The first figure by the OP shows using pin 7 to discharge. In this configuation you need pin 7. Another configuration is to charge the capacitor towards the output, both high & low, as you've shown. In this confdiguration, no pin 7.
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    555 astable

    Coincidentally, I got handed the other day some old throw away boards labelled "RS 434-071" which are pre-printed (not populated) boards for 555 modules. These boards just allow you to build basically the same circuit on a PCB. Not everyone's perfect option, but one way to have these useful...
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    555 astable

    Sorry, don't understand. Pin 7 is usually the internal controlled discharge path, so the capacitor will not discharge if not connected to pin 7.
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    Audio alarm timer, tantalum value issue help

    The circuit runs on 9 volts. So the 10 volt capacitor is fine from a voltage point of view. Electrolytics might have greater leakage current, so the timing may change, or if great, might never time out. If you see the LED change, the timer is working. . If no sound, check the second half...
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    Audio alarm timer, tantalum value issue help

    Not quite sure what you want to know. >>The book recommends a 33uf tantalum 10v capacitor but I have a 33uf 16volt. Actually they are only tantalums I own. Ive tested with a multimeter and it climbs to around 8volts dc and then steadily start dropping. Where does the electrolytic come in? Were...
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    555 astable

    So, if all seems correct, you start trying to work out which part is not right, broken, not as expected. . Substitution. Swap each part for another similar. Start with the ones that if this is not the broken part, that is, there is something else broken, you won't blow up your new substitute in...
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    555 astable

    Well, it's a bit of a mystery. Construction comes next. Did you make what you think you made? :) The silly stuff: Battery the right way round? &c.
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    555 astable

    Just to balance this last point from my own experience. This can be an issue, I know, but buying small quanties, 10, 50 at a time, I've used a lot of such chips including 555 timers purchased from China, personally and from Aliexpress, and not found any that misbehaved so far. Each of us has...
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