Low Power Boost Regulator with Dual Half-Bridge in 3mm × 2mm DFN Drives MEMS and Piezo Actuators

Low Power Boost Regulator with Dual Half-Bridge in 3mm × 2mm DFN Drives MEMS and Piezo Actuators

Advances in manufacturing technology have made it possible for actuators, sensors, RF relays, and other moveable parts to be manufactured at a very small scale. These devices, referred to as MEMS (micro-electro-mechanical systems) or micro-machines, are finding their way into daily life in applications unheard of just a few years ago. MEMS are used in automotive, military, medical and consumer product applications.

Many types of MEMS devices consume very little power to operate and generally require the use of two support circuits, a step-up converter and a dual half-bridge driver. These support circuits must be very small and highly efficient to keep pace with ever-shrinking MEMS applications. To this end, the LT8415 integrates the step-up converter power switch and diode and the dual half-bridge driver in a 12-pin, 3mm × 2mm DFN package. Its novel switching architecture consumes very little power throughout the load range, making it an ideal match for driving low current MEMS.

The LT8415 generates output voltages up to 40V from sources ranging from 2.5V to 16V. The output is then available for the integrated complementary half-bridge drivers and is available via OUT1 and OUT2 (see Figure 1). Each half-bridge is made up of an N-channel MOSFET and a P-channel MOSFET, which are synchronously controlled by a single pin and never turn on at the same time. OUT1 and OUT2 are of the same polarity as IN1 and IN2, respectively. When the part is turned off, all MOSFETs are turned off, and the OUT1 and OUT2 nodes revert to a high impedance state with 20MΩ pull-down resistors to ground.

Figure 1. Simplified block diagram of the LT8415.

2.6V–5V Input to 34V Output MEMS Driver

Figure 2 shows a MEMS driver that takes a 2.6V–5V input and produces a 34V output. This circuit draws very little source current when the dual half-bridge is disabled. The input current is only 320µA at 2.6V_IN and 128µA at 5V_IN. A logic level signal at IN1 and IN2 activates the dual half-bridge switches. Figure 3 shows the turn-on delay and rise time for OUT1 and OUT2 with both half-bridges activated. Figure 4 shows the turn-off delay and fall time with the 200pF and 1nF capacitive loads shown in Figure 2. See the data sheet details for measuring delay time.

Figure 2. 2.6V–5V input to 34V dual half-bridge boost converter.

Figure 3. Turn-on delay and rise time for OUT1 and OUT2.

Figure 4. Turn-off delay and fall time for OUT1 and OUT2.

3V–10V Input to 16V Output MEMS Driver and Bias Supply

Figure 5 shows a 3V–10V input to 16V output converter, where the output drives the dual half-bridge and also provides bias current for other circuitry. The converter in Figure 2 can be used in a similar fashion, but the current available at the output is reduced as the output voltage is increased. See the data sheet for details about maximum output current.

Figure 5. 3V–10V input to 16V dual half-bridge plus 16V output boost converter.

Integrated Resistor Divider

The LT8415 contains an integrated resistor divider such that if the FBP pin is at 1.235V or higher, the output is clamped at 40V. For lower output voltage levels use R1 and R2, calculating their values as instructed by the data sheet. This method of setting the output voltage ensures the voltage divider draws minimal current from the input when the part is turned off.

The LT8415 is an ideal match for driving low power MEMS. It integrates a step-up converter power switch and diode, a complementary dual half-bridge, and a novel switching architecture that minimizes power dissipation.

Об авторах

Jesus Rosales is an applications engineer in Analog Devices’ Applications Group in Milpitas, CA. He joined Linear Technology (now a part of ADI) in 1995 as an associate engineer and was promoted to applications engineer in 2001. He has since supported the boost/inverting/SEPIC family of monolithic converters and some offline isolated application controllers. He received an associate degree in electronics from Bay Valley Technical Institute in 1982.

LR Baggs Anthem

The LR Baggs Anthem acoustic guitar pick up has blown me away. I’m serious. If you haven’t heard this pickup in person, go to your local acoustic guitar dealer and play it immediately! I’m telling you, it is sounds awesome!

Quick Overview

The LR Baggs Anthem is more than your ordinary acoustic guitar pick up. It combines LR Baggs Tru-Mic microphone with their Element piezo style pickup. Their website claims that this combination allows you to have a, “studio mic’d sound wherever you perform.” They are not lying. It really sounds fantastic. I decided to document the sound for you in this post so you can hear for yourself just how good this microphone is. I’m going to provide a few sample sounds of some finger picking and some strumming. I’ll pick and strum the same lick in each demo so you can hear the pickup and microphone’s sound and the acoustic guitar’s sound individually. But first, let’s go over the features of the LR Baggs Anthem.

Controls

The controls for the LR Baggs Antehm are mounted behind the acoustic guitar’s sound hole. The curved face plate closley matches the sound hole’s shape. This curved face plate is very discreet and is the only visible part of the Anthem.

You’re provided a volume control, mix control, phase button, and a battery check. The volume control the forward most roller, and controls, well the volume!

The mix control is the roller closest to the bridge and allows you to blend the sound between the Tru-Mic and Element pickup. With the roller 100% toward the bridge, the Element pickup is isolated, and the Tri-Mic is essentially off or muted. The Element pickup provides a great sound, but being a classic piezo it does not differentiate itself from the pack too much. That’s where the Tru-Mic comes in.

The Tru-Mic is LR Baggs patented microphone. LR Baggs designed this microphone to capture as much of the guitar’s full range as possible. The Tru-Mic pickup is preset the Element pickup supporting the lower frequencies of the guitar. When you roll the Mix control towards the neck, you begin to blend the Element pickup with the sound of the Tru-Mic with Element low frequency support. This is where the Anthem really begins to shine.

Does it Feedback?

Plugged into an amplifier, this pickup sings. It really makes acoustic guitar sound great. I use this exclusively when I play live with my band, roadrunners, and I’ve never had feedback issues. The entire Anthem system, including the 9 volt battery, is so lightweight that I don’t notice it at all.

Speaking of feedback, there is a phase inversion button in case you find yourself getting feedback in a particular room or with a certain PA setup. I’ve never had to use this button for feedback, and when I do use it, I’m usually listening for what sounds best at that moment.

The battery check is another handy feature. To operate it, you push the battery check button, and the green LEDs light up to indicate how much juice the battery has left. There are 5 LEDS, and when all three are green, you got 100% battery juice levels, dude!

I did forget to mention one additional control, and that is the mic trim control. I left this out because L.R. Baggs presets the levels of the mic and the pickup in the factory, and if there are any adjustments to be made, most of us are probably not qualified to do so. I had my technician install the pickup in my Martin Custom D Classic, and I’ve never had to touch the trim.

How Does it Sound?

Fingerpicking

It sounds pretty frigging good. But don’t take my word for it. Listen to the sound clips below to hear for yourself! This first audio clip is of the Element pickup, with the mix control rolled 100% towards the bridge of my Martin Custom D Classic. I’ll start with some fingerpicking, and then I’ll show you how it sounds strumming some chords.

The next clip is also the Element pickup with the mix control rolled 100% toward the bridge, but this time with the phase button activated.

Now, compare this to the Tru-Mic microphone, with the mix control rolled 100% toward the neck.

And the last pickup sound, the Tru-Mic microphone with the mix control 100% rolled toward the neck, but this time with the phase button activated.

Finally, I’m going to share a clip of the guitar recorded acoustically (no pickup). You can listen to the guitar’s natural sound, and compare this to any of the clips above.

Strumming Chords

Below you can hear some simple chords strummed using the LR Baggs Anthem. The first clip is the Element pickup, with the mix control rolled 100% towards the bridge.

The next clip is the Element pickup again with the mix control rolled 100% toward the bridge and the phase inverted.

Now the Tru-Mic Microphone with the mix control rolled 100% toward the neck.

And the last sound, the Tru-Mic microphone with the mix control rolled 100% toward the neck and the phase inverted.

To wrap up, listen to the guitar recorded acoustically to hear how the guitar sounds naturally. You can compare this to the pickup and microphone.

The Wrap Up

The LR Baggs Anthem really impressed me. I can’t tell you how happy I am to have this installed in my acoustic guitar. I would love to have a shoot out with another pickup and see how the Anthem stacks up, because I think the Anthem is hard to beat. They retail at about $300, and I paid about $160 to have it professionally installed by the guys at Gryphon Stringed Instruments in Palo Alto.

This could be the holy grail of acoustic guitar microphone and pickup combinations. If you want to know more about the Martin I played, check out my review of the Martin Custom D Classic. At the end I mention what kinds of strings and picks I use, and also mention the equipment I used to record the audio clips. Thanks for reading, and happy playing!

Deep Pockets: A Guide to Developing Better Time

• Develop a better sense of subdivisions.
• Understand how to play «over the bar line.»
• Learn to target chord tones in a 12-bar blues.

Playing in the pocket is the most important thing in music. Just think about how we talk about great music: It’s «grooving» or «swinging» or «rocking.» Nobody ever says, «I really enjoyed their use of inverted suspended triads,» or «their application of large-interval pentatonic sequences was fascinating.» So, whether you’re playing live or recording, time is everyone’s responsibility, and you must develop your ability to play in the pocket.

So, what is bad time? It’s when people rush and speed up the tempo or drag and slow the tempo down in an unmusical way. If your quarter-note pulse is uneven, you can’t lock in with what the band is doing because the time keeps moving. If somebody’s fills are all wonky and don’t land right, that usually means they are not subdividing and are just stuffing notes into the measure haphazardly. These players don’t realize what is happening. Don’t be one of these players. To develop your own pocket, you will need two things: your guitar and a metronome. A better groove, and a better ability to subdivide the beat, will lead to better phrasing and more control of what you want to play.

The first three examples are designed to eliminate your reliance on the first beat of the measure. Practicing with the metronome on all four beats of the measure is a very common way to practice scales and chord progressions. Remember that in most styles of music, the snare drum is on beats 2 and 4 of the measure. Practice with your metronome as if it’s a snare, where the click is on 2 and 4. (A note about tempo markings: Usually the tempo is listed at a quarter-note level, but with the metronome on beats 2 and 4, it’s marked as a half-note. So, if the half-note tempo is listed as 120 bpm, the quarter-note tempo would be twice that, or 240 bpm.)

Ex. 1 is a G7 arpeggio played in 3rd position, with half-note tempos of 100, 125, and 150 bpm. The recording of this example has a count off with the clicks on 2 and 4. If these tempos are initially too fast, start with a slower tempo where you can play the example cleanly, putting each note directly in between the clicks of the metronome. You can even start with just a single note at a comfortable tempo, getting used to what it sounds and feels like to put a note directly in between the metronome clicks.

Ex. 2 is the A minor pentatonic scale (A–C–D–E–G) in 5th position, played first in half-notes and then again in whole-notes. This example is designed to help you switch gears between different rhythms.

Ex. 3 is the C major scale (C–D–E–F–G–A–B) in 7th position played in half-notes and whole-notes, but at faster tempo. If you practice different types of scales and arpeggios in this way, you’ll discover spots where you may rush or drag the notes.

The last three phrasing exercises are intended to eliminate your need to play on the first beat of the measure. Played over a 12-bar blues in A, each example uses a different rhythm or phrasing structure where you will need to count a lot of empty space to play these rhythms correctly. Ex. 5 is deceptively simple, where you play only on beats two, three, and four of each measure. It takes more concentration than you would think, so be careful that you don’t fall back into playing your usual stuff.

Ex. 6 will develop your ability to play over the bar line, which is simply not starting or ending your phrases directly on beat 1. There’s a lot of space to count, starting each small phrase on the «and» of beat 3, and finishing on the «and» of beat 1 in the next measure.

Ex. 7 aims to expand your phrasing, creating longer lines by playing a two-bar phrase almost entirely in eighth-notes. The challenge to this exercise is beginning on the «and» of one in the first measure and ending on the «and» of four in the second measure. In each of these examples, practice each rhythm by itself on a single pitch with a metronome, focusing on counting the spaces and playing that specific rhythm. Then, try adding different chord tones or scales when that rhythm becomes internalized.

After working on these examples, play over a track and focus on one concept at a time to see if you really have it under your fingers and in your ears. Always remember to keep things simple to begin with. There’s plenty of time to make things complicated later on. Cheers!

Особенности и противопоказания
бриджа

Для украшения прокола переносицы, как правило, используют штангу, на концах которой расположены шарики. Пользоваться широким спросом бридж стал не так уж и давно, и с каждым днем данный вид продолжает набирать обороты.

Такая популярность услуги среди молодого поколения объясняется тем, что бридж — наиболее подходящий пирсинг для самовыражения. Ведь прокол переносицы выглядит необычно, оригинально и эффектно, что само собой притягивает взгляды окружающих и прохожих людей.

Процедура прокола переносицы довольно болезненна, вследствие чего, необходимо предварительное применение анестезии. Болеутоляющее вещество вводится именно в то место, где будет осуществляться прокол. Намного реже препарат анестезии вводится внутривенно.

Важно! При выборе данного вида пирсинга, предварительно необходимо тщательно ознакомится с противопоказаниями. Бридж нежелательно осуществлять людям с тонкой кожей. Важно обращать внимание на сплав из которого изготовляется украшение, если есть риск аллергических реакций, лучше не экспериментировать. Возникновение аллергической реакции может привести к серьезным осложнениям.

Так же осуществлять данный вид прокола запрещено людям, у которых имеются проблемы с органами зрения. Если у человека активно развивается конъюнктивит, ни один квалифицированный специалист не согласиться на работу. Если на переносице имеются шрамы либо ожоги, это тоже затруднит работу мастера.

Так же пирсинг бридж противопоказан людям с инфекционными и прочими заболеваниями кожного покрова, с нарушенной сердечно-сосудистой системой. Беременность и период кормления грудью так же нежелательное время для процедуры прокалывания переносицы.

Предосторожность и возможные последствия

Период заживления переносицы длится довольно долго, полное затягивание прокола может длится около шести месяцев. Частое явление при заживлении бриджа, это отек переносицы, а так же опухоль в области глаз.

Стоит так же заметить, что в первое время после процедуры прокола, лицо будет выглядеть не лучшим образом. Под глазами могут появиться не только опухоль, но и синие круги. Решить проблему с опухолью и отечностью поможет холодный компресс.

Дабы предотвратить риск возникновения отечности, необходимо уметь правильно подобрать украшение. Серьга должна быть удобной и подходить по размеру. Так же важно выбирать гипоаллергенный сплав украшения.

Необходимо понимать, что в области переносицы осуществляется плоскостный прокол, а так как данная зона принимает активное участие в мимике лица, может произойти отторжение украшения. Когда именно тело начнет отторгать серьгу сказать трудно, но данный процесс можно заметить. При отхождении серьги, остаются следы, которые практически не заметны. Как только Вы заметите, что украшение начало мигрировать, необходимо сразу обратиться к мастеру пирсинга. Скорее всего серьгу придется утилизировать.

Но стоит так же заметить, что этого можно избежать. Необходимо тщательно подойти к выбору пирсингиста, который будет строго соблюдать все правила санитарии и гигиены. Нужно грамотно подобрать украшение, и особое внимание уделять уходу за проколотым участок тела.

Особенности ухода за местом прокола

Несмотря на то, что бридж является одним из опасных и довольно болезненных видов пирсинга, все же входит в число самых популярных проколов тела.

Для того, чтобы бридж только радовал Вас и приносил яркие, радостные эмоции, за местом прокола стоит тщательно следить и вовремя обрабатывать антисептическими средствами. Очень важно регулярно обрабатывать пирсинг, и не менять украшение, пока прокол полноценно не затянется. Как же проводить обработку бриджа?

1. На постоянной основе обрабатывать место прокола антисептическим средствами. Хорошо помогают стерилизации и регенерации кожи такие препараты как "Хлоргексидин" и "Мирамистин". Не рекомендовано применение йода, спирта либо зеленки. Данные препараты раздражающе воздействуют на заживаемый участок.
2. Дабы предотвратить инфекционные заболевания, на ночь на участок прокола рекомендовано накладывать небольшое количество антибактериальной мази. Для этого хорошо подойдет "Левомиколь", либо другие его аналоги.
3. При возникновении воспаления, прокол необходимо обрабатывать не реже каждых четырех часов.
4. Лишний раз не прикасаться к месту прокола, не трогать и не двигать серьгу.
5. Ограничить посещение открытых водоемов, саун, бань и бассейнов.
6. Не рекомендовано греть место прокола.
7. На время заживания прокола лучше отказаться от горячей ванны.

Квалифицированные пирсингисты настаивают на том, что пока место прокола окончательно не заживет, смену серьги проводить не стоит. Очень часто люди не дожидаются полноценного затягивания прокола и вынимают серьгу. Что приводит к повторному проколу переносицы, так как прокол очень быстро затягивается без украшения. При неправильных действиях может начаться процесс воспаления участка.

При возникновении воспалительных процессов, которые долгое время не проходят, стоит немедленно обратиться к мастеру пирсинга. Если воспаленные не удается снять антисептическими препаратами и антибактериальными мазями, значит украшение необходимо извлечь и заниматься заживлением самого прокола.

Серьги для бриджа

Просматривая многочисленные фотографии пирсинга бридж, замечаем что самым распространенным украшением для этого вида прокола является штанга.

Обычно по краям штанги размещаются небольшие металлические либо пластмассовые шарики, шипы либо камушки. Штангу выбирают с диаметром 1,6 миллиметров, длина может быть разной. По длине серьгу выбирают индивидуально под клиента, при этом украшение выбирается с запасом в четыре миллиметра в длину, так как участок прокола может отекать.

Для осуществления прокола, специалисты рекомендуют следующий материал для украшений:

1. Медицинский сплав — часто применяемый сплав для украшений в пирсинге. Если у клиента есть аллергия на никелевые сплавы, необходимо подобрать другое украшение;
2. Титан — в медицине титан часто применят для замены костей. Данный материал отлично подходит для серьги пирсинга.
3. Биопластовый материал — пластик, который не содержит в своем составе компоненты способные вызвать аллергические реакции.

После полноценного заживления прокола, когда серьгу можно свободно двигать, первое украшение можно заменить другим, с любым желающим для Вас материалом:

• Золото;
• Серебро;
• Платина;
• Кость;
• Дерево и так далее.

Пирсинг Бридж — болезненный вид пирсинга, но данный вид прокола стоит того терпения. Если Вы приняли решение и выбрали именно бридж, стоит сразу настроить себя на длительный реабилитационный период. После проведения процедуры пирсинга, мастер обязательно предоставит ряд рекомендаций по уходу за проколотым местом. Придерживайтесь данных рекомендаций, уделите особое внимание уходу за пирсингом. Ведь от этого зависит не только будущий внешний вид, но и Ваше здоровье.

6. Yamaha DT-50K

For the end of this short list, here is a product that comes from one of the most renowned names in the industry of musical instruments. This Yamaha DT-50K is a high-quality trigger that comes with a lot of great features. First of all, it offers an excellent sound quality.

Count on amazing response and sensibility. Also, it features a metal body which guarantees excellent sturdiness and years of use.

Still, the mounting system is probably the strongest point of this trigger. The system is quite simple but very effective. Attaching the trigger requires no more than a few moments. It is very safe, so you won’t have to worry about damaging your drum shells. Once mounted, the trigger works perfectly and doesn’t affect the natural drum sound at all.

Types of Drum Triggers

Most of the manufacturers offer their own mounting systems, tough I would say that all of them are very similar. The process of mounting is extremely quick—a matter of seconds, I would say.

Though most of us see drum triggers as studio and home practice devices, these units are actually amazing tools for live performances, especially for small venues where drummers can’t control loud drum heads and where assistance from professional sound engineers is necessary.

If you have a quality drum module, you can adapt electronic sound so well that it will closely mimic acoustic drums.

Some of these devices are actually dual sensitive. In practice, this means that you can pick different kinds of sounds. For example, Roland RT-30HR is a dual trigger, which recognizes and separates rim and main head hits. This is really great for sound and effect diversity.

Of course, these are just some of many great things about drum triggers; the benefits are numerous.

Acoustic Drum Trigger Module

Once you get drum triggers, you are halfway through the process. The other part of the process would be getting a trigger module (or you could also use a sample pad or electronic drum module). They usually feature a bunch of sounds, on-board effects, etc. Other important parts of the trigger module are things like trigger inputs, PA and headphone outputs, MIDI ports, etc.

One of the most popular acoustic trigger modules is Roland TM-2. This is quite an affordable unit, characterized by the amazing simplicity of use. Setting up this module seems effortless since the number of buttons is minimal. Since functionality is the strongest point of this unit, there is a pretty large number of built-in sounds—around 160. There are also 11 effects as well as several other functions. Also, it comes with an SD card slot, so you can easily import your favorite presets.

When it comes to connectivity, Roland TM-2 comes with one PA output, one headphone output, and two MIDI ports (in and out). Another convenient feature is that the unit can be power supplied both by cord and batteries, which is great for those who appreciate portability.