What is the simplest circuit that can be used to generate a 5V TTL signal with fixed frequencies such as 0.5Hz, 1Hz, 50Hz, 100Hz, 500Hz, 1kHz, 5kHz, 10kHz..?
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2\$\begingroup\$ 555-timer based ones? For lower frequencies at least. \$\endgroup\$– Eugene Sh.Commented Feb 12 at 15:16
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1\$\begingroup\$ Do they need to be phase locked, so that the 50Hz source is exactly fifty times the frequency of 1Hz, with edges that coincide etc.? \$\endgroup\$– Simon FitchCommented Feb 12 at 15:17
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1\$\begingroup\$ @Shamooooot that happens to sound like a good range of options for a clocking source to a Ben Eater style CPU. \$\endgroup\$– periblepsisCommented Feb 12 at 16:01
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1\$\begingroup\$ A clock source driving a string of 74xx90's or 74xx390's is the common answer. Note that some of the output frequencies will not be symmetrical (50/50) square waves. \$\endgroup\$– AnalogKidCommented Feb 12 at 16:13
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1\$\begingroup\$ @Shamooooot I'm also a little bothered by the such as part of your statement. It sounds as though those are not only optional but that there may be others as yet unstated, as well. In which case, this is a very wide-open question. \$\endgroup\$– periblepsisCommented Feb 12 at 20:03
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2 Answers
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the simplest circuit I could think of consists of two components:
- decoupling capacitor (typically, 100 nF ceramic)
- microcontroller (something between an Attiny8 and an STM32)
you can then select the frequency you want by tying pins to ground or supply voltage.
I don't think it will get simpler than 2 components, of which one is already a non-critical decoupling capacitor.
Especially 0.5 Hz will be very hard to achieve with things like 555 timer ICs, as it's very slow for timers based on how long it takes to charge a capacitor.
answered Feb 12 at 15:27
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1\$\begingroup\$ If you answer a question it may be useful to also upvote it. (This is NOT a moderator comment - just a thought as an individual). \$\endgroup\$– Russell McMahon ♦Commented Feb 27 at 0:44
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1\$\begingroup\$ @RussellMcMahon to personally address that: I always consider that (I think Neil probably was, as well); but the question isn't that in-depth, or pre-researched, in this case. But you're right, I should probably generally be more generous with my upvoting \$\endgroup\$ Commented Feb 27 at 10:43
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I'm getting a base-10 vibe from your question.
I suggest a top-oscillator, maybe crystal based, at some multiple of 10 frequency, with a cascade of dividers after it. You can buy complete oscillators, or you can buy a ceramic or crystal resonator, and wrap it round a logic gate (with a couple of small Cs and a big R) to make an oscillator. For the chain of dividers, I suggest something like 74xx390 dividers, these contain two /2 and two /5 dividers, for a total division of /100 per package. Select which output you need with jumpers.
Far simpler is an MCU board, perhaps an Arduino, and program the appropriate divider.
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1\$\begingroup\$ If you answer a question it may be useful to also upvote it. (This is NOT a moderator comment - just a thought as an individual). \$\endgroup\$– Russell McMahon ♦Commented Feb 27 at 0:45