apparat_20_construction_blog
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apparat_20_construction_blog [2007/01/28 12:10] seppoman |
apparat_20_construction_blog [2007/11/17 16:15] (current) smashtv moved images to local |
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| I really wanted a "Plug'n'Go" thing for stage use, so everything must fit into the phone. This means (of course) the phone needs to offer some space inside and has to look cool. I chose this phone - it's an 80ies phone built by SEL from the "design" line of the Deutsche Telekom. It emerged from a phone for disabled people, hence the really BIG dial buttons. | I really wanted a "Plug'n'Go" thing for stage use, so everything must fit into the phone. This means (of course) the phone needs to offer some space inside and has to look cool. I chose this phone - it's an 80ies phone built by SEL from the "design" line of the Deutsche Telekom. It emerged from a phone for disabled people, hence the really BIG dial buttons. | ||
| - | {{http://www.seppoman.de/apparat20/phone1.jpg}} | + | {{seppoman:phone1.jpg}} |
| == Vocoder == | == Vocoder == | ||
| Line 19: | Line 19: | ||
| The vocoder has to be as small as possible. Mostly, vocoding is found in (at least) 9.5" FX units. Standalone vocoders (like the MAM VF11 or DIY versions) are normally analogue and even bigger units. Then I found the Alesis Metavox - it´s the smallest (14 x 8 cm) and also cheapest vocoder existing (got it for 30 EUR new). Most of its functions are not really useful for music, all around the internal oscillator/LFO is more like a DJ toy. But the sound quality in external mode is quite good. | The vocoder has to be as small as possible. Mostly, vocoding is found in (at least) 9.5" FX units. Standalone vocoders (like the MAM VF11 or DIY versions) are normally analogue and even bigger units. Then I found the Alesis Metavox - it´s the smallest (14 x 8 cm) and also cheapest vocoder existing (got it for 30 EUR new). Most of its functions are not really useful for music, all around the internal oscillator/LFO is more like a DJ toy. But the sound quality in external mode is quite good. | ||
| - | {{http://www.seppoman.de/apparat20/alesis1.jpg}} | + | {{seppoman:alesis1.jpg}} |
| == Synthesizer == | == Synthesizer == | ||
| Line 36: | Line 36: | ||
| This is what the phone looks like inside - you can see there's quite some room in there. | This is what the phone looks like inside - you can see there's quite some room in there. | ||
| - | {{http://www.seppoman.de/apparat20/phone2.jpg}} | + | {{seppoman:phone2.jpg}} |
| After throwing everything out, I examined the keyboard to find out how to use it. | After throwing everything out, I examined the keyboard to find out how to use it. | ||
| - | {{http://www.seppoman.de/apparat20/phone3.jpg}} | + | {{seppoman:phone3.jpg}} |
| Under the control board there is a simple 4x3 button matrix (without diodes - but that's no problem, it won't be necessary to press more than one button at the same time). | Under the control board there is a simple 4x3 button matrix (without diodes - but that's no problem, it won't be necessary to press more than one button at the same time). | ||
| - | {{http://www.seppoman.de/apparat20/phone4.jpg}} | + | {{seppoman:phone4.jpg}} |
| Because the contacts for the # and * buttons were not connected, I had to solder a few thin wires and I rewired the connector: | Because the contacts for the # and * buttons were not connected, I had to solder a few thin wires and I rewired the connector: | ||
| - | {{http://www.seppoman.de/apparat20/phone5.jpg}} | + | {{seppoman:phone5.jpg}} |
| - | {{http://www.seppoman.de/apparat20/phone6.jpg}} | + | {{seppoman:phone6.jpg}} |
| There's some space under the keypad, so I decided to mount the Core directly onto the backside of the keypad - the OPL3 module will still fit beneath it.\\ | There's some space under the keypad, so I decided to mount the Core directly onto the backside of the keypad - the OPL3 module will still fit beneath it.\\ | ||
| Line 56: | Line 56: | ||
| The keypad matrix is connected to J5. There are 10k PullDown resistors where the three columns are connected. The OPL3 board wires were a bit tricky - the pin order is swapped because of the board being mounted heads-down. | The keypad matrix is connected to J5. There are 10k PullDown resistors where the three columns are connected. The OPL3 board wires were a bit tricky - the pin order is swapped because of the board being mounted heads-down. | ||
| - | {{http://www.seppoman.de/apparat20/core1.jpg}} | + | {{seppoman:core1.jpg}} |
| - | {{http://www.seppoman.de/apparat20/core2.jpg}} | + | {{seppoman:core2.jpg}} |
| - | {{http://www.seppoman.de/apparat20/core3.jpg}} | + | {{seppoman:core3.jpg}} |
| == Software changes for the matrix keyboard == | == Software changes for the matrix keyboard == | ||
| Line 191: | Line 191: | ||
| I milled away most of the mounting posts in the phone. All jacks and the OPL3 board were installed and the wiring for power and MIDI was done: | I milled away most of the mounting posts in the phone. All jacks and the OPL3 board were installed and the wiring for power and MIDI was done: | ||
| - | {{http://www.seppoman.de/apparat20/phone8.jpg}} | + | {{seppoman:phone8.jpg}} |
| As the keypad descends towards the front, I laid all larger parts (mainly the electrolytics) flat on the boards. The clearance between the boards is quite narrow but sufficient not to fear any shorts etc. | As the keypad descends towards the front, I laid all larger parts (mainly the electrolytics) flat on the boards. The clearance between the boards is quite narrow but sufficient not to fear any shorts etc. | ||
| - | {{http://www.seppoman.de/apparat20/phone9.jpg}} | + | {{seppoman:phone9.jpg}} |
| - | {{http://www.seppoman.de/apparat20/phone10.jpg}} | + | {{seppoman:phone10.jpg}} |
| Now, the phone contains a fully functional MBFM 8-) | Now, the phone contains a fully functional MBFM 8-) | ||
| Line 205: | Line 205: | ||
| After disassembling the Metavox, I found out that there are two boards inside this tiny unit. The lower one has all the jacks and pots mounted and contains the PSU, the DSP and analog cirquits. The upper one has the buttons, LEDs and a small Philips MicroController. I will mount them above each other like in the original unit, but I want them to consume less space, so I started by desoldering all pots and jacks from the lower board. The three unused pots are replaced by two resistors to simulate a pot. The Siblance pot gets a connector. | After disassembling the Metavox, I found out that there are two boards inside this tiny unit. The lower one has all the jacks and pots mounted and contains the PSU, the DSP and analog cirquits. The upper one has the buttons, LEDs and a small Philips MicroController. I will mount them above each other like in the original unit, but I want them to consume less space, so I started by desoldering all pots and jacks from the lower board. The three unused pots are replaced by two resistors to simulate a pot. The Siblance pot gets a connector. | ||
| - | {{http://www.seppoman.de/apparat20/alesis2.jpg}} | + | {{seppoman:alesis2.jpg}} |
| The Metavox originally runs from a 9V AC wall wart, but the MBFM PSU delivers only 5V and +/-12V. So I followed the power traces - the 9V AC is divided in +9V and -9V DC via two diodes and there's a regulator bringing the +9V down to 5V DC. The +/- 9V are only used for the output opamp (standard TL series) that easily takes much higher voltages. So I desoldered the regulator (top of the following picture) and the diodes and put connectors for 5V, GND and +/-12V on the board. This way the output headroom will be just a bit higher. | The Metavox originally runs from a 9V AC wall wart, but the MBFM PSU delivers only 5V and +/-12V. So I followed the power traces - the 9V AC is divided in +9V and -9V DC via two diodes and there's a regulator bringing the +9V down to 5V DC. The +/- 9V are only used for the output opamp (standard TL series) that easily takes much higher voltages. So I desoldered the regulator (top of the following picture) and the diodes and put connectors for 5V, GND and +/-12V on the board. This way the output headroom will be just a bit higher. | ||
| - | {{http://www.seppoman.de/apparat20/alesis3.jpg}} | + | {{seppoman:alesis3.jpg}} |
| This is the lower board mounted and connected to the audio in/out jacks. Again, the capacitors are laid flat. | This is the lower board mounted and connected to the audio in/out jacks. Again, the capacitors are laid flat. | ||
| - | {{http://www.seppoman.de/apparat20/phone11.jpg}} | + | {{seppoman:phone11.jpg}} |
| The second board connected. Behind the keypad there's the Siblance pot. | The second board connected. Behind the keypad there's the Siblance pot. | ||
| - | {{http://www.seppoman.de/apparat20/phone12.jpg}} | + | {{seppoman:phone12.jpg}} |
| The pot and jacks seen from behind: | The pot and jacks seen from behind: | ||
| - | {{http://www.seppoman.de/apparat20/phone13.jpg}} | + | {{seppoman:phone13.jpg}} |
| === Chapter 2 (Sept 5, 2006) === | === Chapter 2 (Sept 5, 2006) === | ||
| Line 231: | Line 231: | ||
| First I just put a piece of foam with a hole for the capsule into the handset, but the problem is that with such a small capsule in it, the handset makes a very hollow-sounding cave and is very sensitive to feedback. Glueing the capsule directly behind the grid is also no good because the mic gets very susceptible to pops and breath. So I took the plastic ring that held the original capsule. I laid it onto a baking paper and filled it with hot glue. After cooling down I got a plain surface that could be mounted easily with 2-3 mm distance to the grid. I drilled a hole into the glue and fixed the capsule with a little more of hot glue. Voila: | First I just put a piece of foam with a hole for the capsule into the handset, but the problem is that with such a small capsule in it, the handset makes a very hollow-sounding cave and is very sensitive to feedback. Glueing the capsule directly behind the grid is also no good because the mic gets very susceptible to pops and breath. So I took the plastic ring that held the original capsule. I laid it onto a baking paper and filled it with hot glue. After cooling down I got a plain surface that could be mounted easily with 2-3 mm distance to the grid. I drilled a hole into the glue and fixed the capsule with a little more of hot glue. Voila: | ||
| - | {{http://www.seppoman.de/apparat20/handset1.jpg}} | + | {{seppoman:handset1.jpg}} |
| - | {{http://www.seppoman.de/apparat20/handset2.jpg}} | + | {{seppoman:handset2.jpg}} |
| == the bypass == | == the bypass == | ||
| Line 239: | Line 239: | ||
| The audio jacks are all wired so that you can insert other sources to the vocoder. | The audio jacks are all wired so that you can insert other sources to the vocoder. | ||
| - | {{http://www.seppoman.de/apparat20/outboard.jpg}} | + | {{seppoman:outboard.jpg}} |
| I found out that it´s a bit difficult to use the built-in vocoder bypass. The debouncing of the buttons is not very good on the alesis, so it happens quite often that you switch the bypass on and off again with one button press. When used "the normal way", this is no big problem because you check the bypass LED anyway. But triggering this button from the core module it could happen that the pickup and the bypass state get "asynchronous". Checking the LED state from the core is complicated, too. The LED is part of a matrix so there´s no simple way to measure on and off.\\ | I found out that it´s a bit difficult to use the built-in vocoder bypass. The debouncing of the buttons is not very good on the alesis, so it happens quite often that you switch the bypass on and off again with one button press. When used "the normal way", this is no big problem because you check the bypass LED anyway. But triggering this button from the core module it could happen that the pickup and the bypass state get "asynchronous". Checking the LED state from the core is complicated, too. The LED is part of a matrix so there´s no simple way to measure on and off.\\ | ||
| So I decided to do it in the analogue domain by using a 4053 chip. This is a 3x SPDT (dual throw) chip for analogue signals, similar to the 1x8 chip 4051 used in the MBHP AIN module. One problem with this chip is that it doesn´t work with +/-12 V. The standard 74hc4053 (e.g. from TI) takes only 5V but I happened to have left over a few max4053 ICs from Maxim from my last sample order. They have better specs and can take +/- 8V supply. So I ordered a pair of 78l08/79l08 regulators and built a little +/- 8V supply for the max4053. You can see it in the next photo on the left side. The original pickup switch applies 5V or ground to two of the control pins so that the 4053 switches between vocoder and direct synth out (this is the yellow and purple wires on the outboard). The bypass works quite well with only a very silent cracking sound (when switching). | So I decided to do it in the analogue domain by using a 4053 chip. This is a 3x SPDT (dual throw) chip for analogue signals, similar to the 1x8 chip 4051 used in the MBHP AIN module. One problem with this chip is that it doesn´t work with +/-12 V. The standard 74hc4053 (e.g. from TI) takes only 5V but I happened to have left over a few max4053 ICs from Maxim from my last sample order. They have better specs and can take +/- 8V supply. So I ordered a pair of 78l08/79l08 regulators and built a little +/- 8V supply for the max4053. You can see it in the next photo on the left side. The original pickup switch applies 5V or ground to two of the control pins so that the 4053 switches between vocoder and direct synth out (this is the yellow and purple wires on the outboard). The bypass works quite well with only a very silent cracking sound (when switching). | ||
| - | {{http://www.seppoman.de/apparat20/board3.jpg}} | + | {{seppoman:board3.jpg}} |
| == the speaker == | == the speaker == | ||
| Line 250: | Line 250: | ||
| I thought it would be nice and trashy if the phone could make sound on its own, so I searched for a simple amplifier cirquit. I found [[http://home.arcor.de/k.arenfeld/html/transamp.html|this one]] (german page). It delivers enough power to drive a small speaker. At the moment, I´m using a little PC beeper speaker that sounds really trashy, but there´s a bit more room above the vocoder (behind the grill on the panel), so I will order a larger speaker soon. The speaker is of cause deactivated when a cable is plugged into the audio out. Here´s the amp: | I thought it would be nice and trashy if the phone could make sound on its own, so I searched for a simple amplifier cirquit. I found [[http://home.arcor.de/k.arenfeld/html/transamp.html|this one]] (german page). It delivers enough power to drive a small speaker. At the moment, I´m using a little PC beeper speaker that sounds really trashy, but there´s a bit more room above the vocoder (behind the grill on the panel), so I will order a larger speaker soon. The speaker is of cause deactivated when a cable is plugged into the audio out. Here´s the amp: | ||
| - | {{http://www.seppoman.de/apparat20/board2.jpg}} | + | {{seppoman:board2.jpg}} |
| and the whole amp/bypass board in its current state: | and the whole amp/bypass board in its current state: | ||
| - | {{http://www.seppoman.de/apparat20/board1.jpg}} | + | {{seppoman:board1.jpg}} |
| everything connected: | everything connected: | ||
| - | {{http://www.seppoman.de/apparat20/phone14.jpg}} | + | {{seppoman:phone14.jpg}} |
| - | {{http://www.seppoman.de/apparat20/phone15.jpg}} | + | {{seppoman:phone15.jpg}} |
| To be continued 8-) | To be continued 8-) | ||
apparat_20_construction_blog.txt · Last modified: 2007/11/17 16:15 by smashtv
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