Post AdIyJ6fDoCRIQCGjom by NohatCoder@mastodon.gamedev.place
(DIR) More posts by NohatCoder@mastodon.gamedev.place
(DIR) Post #AdIiyVodbJdZ2EOYUK by tedchoward@mastodon.social
2023-12-29T02:10:07Z
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Well, I spend the afternoon building my audio circuit on a breadboard. I connected it to a 6522 VIA, and……nothing!#retrocomputing #electronics
(DIR) Post #AdIiyX6OolRH1biFoO by tedchoward@mastodon.social
2023-12-29T02:13:07Z
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The circuit consists of a SN75489 and an LM386. I’m not sure if the issue is with computer <=> SN75489SN76489 <=> LM386or something else#retrocomputing #electronics
(DIR) Post #AdIiyXw9iKq5c7vaU4 by tedchoward@mastodon.social
2023-12-29T02:14:34Z
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I think the next steps are to remove my homebrew computer from the equation, and connect the circuit directly to an arduino #retrocomputing #electronics
(DIR) Post #AdIiyYmcZGo4EqTUGG by tedchoward@mastodon.social
2023-12-29T03:47:45Z
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Ok, I hooked the circuit up to an Arduino. Nada.Next, I connected the SN76489 directly to a powered speaker (bypassing the LM386 amp). Nothing.Actually, it's not "nothing”, its' actually a low tone. I can't even silence it. Is the chip bad? #retrocomputing #electronics
(DIR) Post #AdIiyat4kF9qlRVfbE by tedchoward@mastodon.social
2023-12-29T03:48:28Z
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The chip was bad. I replaced it, and I get the tones I was expecting.Then I reconnect the amp: no sound. #retrocomputing #electronics
(DIR) Post #AdIiybhlhlhvIfE9c8 by tedchoward@mastodon.social
2023-12-29T03:50:58Z
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This is my sound circuit. Am I doing something obviously stupid? #retrocomputing #electronics
(DIR) Post #AdIiycaMQnNO1ylkhs by tedchoward@mastodon.social
2023-12-29T04:14:53Z
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Ok, I fiddled with the potentiometer and got a sound from the amp, but it was pretty nasty sounding. Also, I only get a sound when the pot is in the middle. Too tight or too loose, and I get no sound at all. (Not what I was expecting). Also, my "working” SN76489 may have just bit the dust :( #retrocomputing #electronics
(DIR) Post #AdIiydRBGPcwfnTw2K by tedchoward@mastodon.social
2023-12-29T05:17:33Z
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Ok, it technically works, but it doesn’t sound great. Also, any adjustment I make to the volume pot does’t seem to make a difference in volume. I do get a cool siren sound when I turn it down low (?).Anyway, progress!#retrocomputing #electronics
(DIR) Post #AdIiyeGw9z1lGJhGi0 by tedchoward@mastodon.social
2023-12-29T05:31:29Z
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Here's the my updated schematic.#retrocomputing #electronics
(DIR) Post #AdIiyex7d8ltN9QxSi by penguin42@mastodon.org.uk
2023-12-29T12:03:21Z
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@tedchoward Why is C3 there? (I can imagine a small constant R there to not be shorting the output with the pot at one end; but I'm also not an analogue person). Also, did you intend to have your data in mirrored?
(DIR) Post #AdIiyfPTvhSMn6hbfM by tedchoward@mastodon.social
2023-12-29T05:31:30Z
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Here’s a vid of the siren sound. I think I’m bumping up on my knowledge of electricity.#retrocomputing #electronics
(DIR) Post #AdIyJ6fDoCRIQCGjom by NohatCoder@mastodon.gamedev.place
2023-12-29T14:55:03Z
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@penguin42 @tedchoward I wouldn't expect C2 or C4 to be there either.
(DIR) Post #AdMt9jvplaseJ5pSc4 by tedchoward@mastodon.social
2023-12-29T23:58:39Z
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Thank you so much to everyone for their suggestions. I have sooooo much to learn. I made some adjustments based on the suggestions, and now I have something closer to what I was expecting.#retrocomputing #electronics
(DIR) Post #AdMt9kZXNydiIEPAUy by tedchoward@mastodon.social
2023-12-29T23:59:53Z
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And here's the latest schematic.#retrocomputing #electronics
(DIR) Post #AdMt9lKKa04OdMIXR2 by tedchoward@mastodon.social
2023-12-31T04:35:26Z
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I spent a good portion of the day looking at schematics of machines that used the SN76489, to see how they built their amplifier circuits. This one is from the Tandy 1000. I tried it out on a breadboard, and it works, but 1) there's a lot of hiss coming out of the speaker, and 2) it sounds “louder” than I expected.How much of the “hissing” sound is due to my use of solderless breadboards?#retrocomputing #electronics
(DIR) Post #AdMt9lzo5nFMhzhf5E by penguin42@mastodon.org.uk
2023-12-31T12:16:17Z
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@tedchoward The BBC B's amp setup seems way more complex for no good reason - about half way up, just in from the left side:https://stardot.org.uk/forums/download/file.php?id=34879&sid=fe285c3280c7dca2bce51a6dc91cd7aa&mode=view
(DIR) Post #AdMt9n3k8dzQ0UYJrE by tedchoward@mastodon.social
2023-12-31T04:39:46Z
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Video of the Tandy circuit.#retrocomputing #electronics
(DIR) Post #AdMt9pBGFfBwaO5Lqy by tedchoward@mastodon.social
2023-12-31T04:46:57Z
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I left a capacitor (C7) off the last schematic (it's on the breadboard, and in the Tandy docs).#retrocomputing #electronics