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morris_minor wrote:
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A remote control |
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TheScorpionsTale 
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Joined: 02 Jan 2021 Location: Oxfordshire, UK Status: Offline Points: 284 |
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 Posted: 02 Dec 2022 at 10:21pm |
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 Actually, I was waiting for someone to suggest a jukebox... And yes, we have rather hijacked your thread, Graham, apologies.
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Graham
SL1200 II with SME M2-9R and various carts / Revelation M with PSU-1 / Cyrus amp, CD and streamer / Kralk Audio BC30-3 Floorstanders / Bitzie and Lautus USB |
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Fatmangolf
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Joined: 23 Dec 2009 Location: Middlesbrough Status: Offline Points: 8629 |
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Posted: 03 Dec 2022 at 8:06am |
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I am interested in the remote control project.
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Jon
Open mind and ears whilst owning GSP Genera, Accession M, Accession MC, Elevator EXP, Solo ULDE, Proprius amps, Cusat50 cables, Lautus digital cable, Spatia cables and links, and a Majestic DAC. |
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Graham Slee
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Retired Joined: 11 Jan 2008 Location: South Yorkshire Status: Offline Points: 16112 |
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Posted: 03 Dec 2022 at 7:39pm |
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Must be seven years ago when I prototyped the remote control circuit pictured on the stripboards shown in the image.  The problem back then was trying to obtain a trendy looking remote control enclosure, getting everything to fit, how to machine it and how to get somebody to make a pseudo membrane graphic. Once upon a time I had all the facilities to do all the above, but that was a long time ago, and it ran out of money because nobody in the UK wanted that sort of service. But it can be made as a hobby electronics project, so I may as well share it with those who'd like to try it. I've read the replies so far, that few so far value the idea, but I still think it worth having a go at. The only things that I'll have to sub out, is a thin aluminium graphics plate with two square holes, and the firm who does the Voyager panel can do that; and a PCB and that can come from our regular supplier (both in the UK). The battery will be a 9V E-cell, and the easily obtainable case has a battery drawer. So, next job will be to draw the circuit diagrams of the remote and receiver circuits, and modify the remote for the larger 9V voltage. You can see it's been a long time by the corrosion built up on the middle 1.5V battery.
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That none should be able to buy or sell without a smartphone and the knowledge in how to use apps
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Graham Slee
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Retired Joined: 11 Jan 2008 Location: South Yorkshire Status: Offline Points: 16112 |
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Posted: 04 Dec 2022 at 11:57am |
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The HT12E is intended to drive an RF transmitter, but here it's used to drive an infra-red transmitter. Ideally a HT12A would be used which drives an IR LED via a transistor at the optimal IR remote frequency, except it is no longer made. The reason is perhaps that few used it as an IR remote controller.  The Holtek HT12 ICs are mostly used as garage door openers. But using the HT12E encoder with an IR LED output, it is unlikely it's going to open or close a garage door, and definitely not from inside your home. Likewise, the HT12D decoder inside the item being remote controlled, isn't going to be affected by an RF garage door opener. And even if a neighbour has an optical garage door opener (if such a thing exists), its range won't be sufficient to turn your volume up or down. There are also a number of addresses (key codes) that can be chosen, which have to match with the same addresses on the decoder. Below is the circuit I prototyped around 7 years ago. There are things I've forgotten about how it works, but I shall have a try. The other IC is the CMOS version of the NE555 timer IC (the 7555) which uses very little current so as to extend remote control battery life. The 7555 reset is held low until HT12E data out goes high, enabling the 7555 which operates as an astable multivibrator (oscillator) with frequency around 40kHz, and a 50:50 duty cycle. The HT12E output is at 1.5kHz, so its 1's are "muxed" into around 13 pieces by the IR LEDs. The decoder at the other end will read it as 1.5kHz ish. The IR LEDs are run at high frequency to enable them to have more current than they're limited to if on at DC. At 50:50 ratio they can run at 200mA. A single pulse can do 1 amp, but then it's all over, which isn't much use, is it? On the 6V supply I calculated 130mA, and that gives a radiant intensity of around 100mW per IR LED. It was sufficient to be decoded at a distance of 20 feet with the remote pointing backwards, such that the IR was being reflected by the rear wall. Should be sufficient for any domestic situation. The power hungry part of the remote is obviously the LEDs and the Darlington configured driver transistors consume a few mA's too. But that's only during operation, and with the 7555 reset pin at logic 0, there's no turn on current to the transistor bases. That leaves only the quiescent current of the 7555 and the HT12E. The static supply current of the 7555 is typically 50uA and the HT12E is about 2uA. So, looking at a battery datasheet we see with a 10k load the battery life to 7.5V is 18 days continuous. That's a current of 900uA, and here we have 52uA. All other things being equal, then the battery should last 311 days, or over 10 months. Is that good enough? It would be nice if it were something like 2 years, but I wonder how. The HT12E can be powered via the diode matrix, by linking the transmit enable (negative going) to the Vss (-Ve) supply pin. But that only saves 2uA. We could try powering the 7555 the same way, but there's the possibility it would glitch, sending the wrong code. So the 7555 has to be kept on all the time to be ready. And that leads me to D1 in the diagram, and right now I haven't a clue why I put it there. That's my memory for you.
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That none should be able to buy or sell without a smartphone and the knowledge in how to use apps
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Ash
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Joined: 18 Mar 2013 Location: Dorset Status: Offline Points: 4316 |
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Posted: 04 Dec 2022 at 12:02pm |
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A simple slide switch to disconnect the batteries from the circuit when not in use, to extend battery life?
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We do not see things as they are. We see things as we are.
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Graham Slee
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Retired Joined: 11 Jan 2008 Location: South Yorkshire Status: Offline Points: 16112 |
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Posted: 04 Dec 2022 at 12:14pm |
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Ah yes, I remember. Vss should not be less than transmit enable, so to ensure it's always 0.6V above 0V, the current for the 7555 runs via it.
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That none should be able to buy or sell without a smartphone and the knowledge in how to use apps
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Graham Slee
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Retired Joined: 11 Jan 2008 Location: South Yorkshire Status: Offline Points: 16112 |
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Posted: 04 Dec 2022 at 12:22pm |
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Yes, I think you're right.
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That none should be able to buy or sell without a smartphone and the knowledge in how to use apps
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