Zalman HD-160 and Accompanying Products

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• Stele - Monday, April 3, 2006 - link

  Good post, well said.
  
  As for using BJTs in audio power amps, I agree with you. It's a good thing... properly selected and implemented, they're generally known to give better sound than FETs (especially in the form of substantially lower distortion and noise figure), as much as triodes/vacuum tubes have excellent distortion and noise characteristics. I used an all-discrete, all-BJT design for an audio power amp competition several years ago; trickier to get right but ultimately satisfying sound quality compared to some designs that took the short cut and dropped in power-amp ICs (mostly from ST, IIRC). :P

• Stele - Sunday, April 2, 2006 - link

  Hi topher42,
  
  

  quote:
  

  ---

  What are you calling integrated?
  Most power fets are one transistor and nothing else in the package.
  Not much integration.

  ---

  
  
  Now how did that slip by me... yes, you're perfectly right. Was trying to be careful not to make that mistake but in the end still tripped on that common misuse of the term. Thank you for pointing it out, I stand corrected :)
  
  20kW amps??? That's powerful alright, no surprise about being a headache to keep cool :)
  
  I mentioned TO-3's along with the other packages to illustrate my point that discrete MOSFETs don't always have to come in 3-legged form, though you're right that they're a big too big for motherboard mobos.
  
  

  quote:
  

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  The EE's I deal with that don't know a fet from an asic are usually the digital
  designers designers that never get closer to a part than their VHDL code.

  ---

  
  
  I see your point, and it kind of explains certain things nowadays... oh well, gone were the hands-on approach of the good old days :P
  
  
  Hi Clauzii
  
  As with topher42 you're right that a discrete MOSFET is not an 'IC', srictly-speaking. I really must be more careful not to mix them up!
  
  However, a MOSFET is not really a "constructional technique in a transistor"; rather, it is a transistor (the most common type of FET, of which there are several kinds) that is made using a particular constructional technique (metal/polycrystalline on gate oxide on silicon etc as opposed to bipolar junctions on BJTs) and that works using a particular method of operation (field effect, as opposed to BJTs). :)
  
  
  Hi AnnonymousCoward,
  
  

  quote:
  

  ---

  Most basic, yes, but not the most common.

  ---

  
  
  Granted not the most common in the objective sense, and you may not need to work with them much unless you're involved in, say, power circuitry design. After all, you did mention that you normally use BJTs more. :)
  
  However, it is really common enough in terms of availability and application that it's about universally known, like the 'regular' BJT, especially in (but not limited to) the semiconductor community/industry. Besides, major semiconductor companies sport hundreds to more than a thousand of such devices in their product lists and they're used in an enormous number of electronic devices, from handphones to motherboards to power amplifiers (audio and electrical).
  
  

  quote:
  

  ---

  So, in power-controlling applications, when are discrete MOSFETs used and when are relays used?

  ---

  
  
  MOSFETs are used in many (dare I say most?) modern power supply applications in electronic devices these days, especially in switch-mode (as opposed to linear) power supplies. Briefly, the MOSFETs in such power supplies are used as digital 'switches' that are rapidly turned on and off a hundred or more times a second to provide power - the amount of power required is varied by changing their duty cycle (how long they stay ON or OFF). This is a whole field by itself, so no-one can blame you if you're not thoroughly familiar with it (I don't pretend to be either! :P).
  
  Relays are used as mechanical switches that isolate two or more circuits yet allow one to control the other(s). A common (but certainly not only use is to allow a low-voltage low-current circuit to control/switch a high-voltage high-current circuit, e.g. when you use a battery-powered light-sensing circuit to turn your room light on.
  
  Opto-couplers and FETs (in the form of solid-state relay ICs) can do the job too, but relays are cheap, readily available, fairly reliable, easy to troubleshoot and generally can handle more current and voltage than a semiconductor counterpart. Of course, relays are bulky, noisy, can introduce damaging surges in the energising circuit when switching on and off (due to the inductance of the coil), and cannot switch as fast as a semicon equivalent, but that's the way it is :)

• Clauzii - Sunday, April 2, 2006 - link

  To repeat myself:
  
  MOS-FET is a constructional technique in a transistor, be it a small one inside a IC or a single "gate" in a device.
  
  An IC is more than one component in the same housing. The MOS-FETs used on mobos are NOT ICs, but Field Effect Transistors made using Metal On Silicon process.

• Clauzii - Sunday, April 2, 2006 - link

  PS: When do DT check up on their f...... Forum System - it´s flawed like h... :)

• Clauzii - Sunday, April 2, 2006 - link

  To repeat myself:
  
  <b>MOS-FET is a constructional technique in a transistor, be it a small one inside a IC or a single "gate" in a device. </b>
  
  An IC is more than one component in the same housing. The MOS-FETs used on mobos are NOT ICs, but Field Effect Transistors made using Metal On Silicon process.

• topher42 - Sunday, April 2, 2006 - link

  stele.
  
  "especially since a MOSFET is an IC."
  
  What are you calling integrated?
  
  Most power fets are one transistor
  and nothing else in the package.
  
  Not much integration.
  
  Most of the 6 pin devices I have used
  were for low current noise differential
  inputs were you wanted identical devices
  and temperature tracking.
  
  And I have used the big packages when
  designing and building 20 kilowatt
  amplifiers. Pain to cool....
  
  I was pointing out that the bios would
  have a problem controlling the cpu voltage
  without power fets. to3's would be a
  little big for that app.
  
  The EE's I deal with that don't know a
  fet from an asic are usually the digital
  designers designers that never get closer
  to a part than their VHDL code.

• Clauzii - Saturday, April 1, 2006 - link

  Nice with a guy that knows what he´s talking about :)
  Also, almost all amplifiers for professional use (including old estimated Hafler P500, Crown, Ampeq etc.) are build whith MOS-FETs in single TO-3 (metal) etc. housings.
  MOS-FET is a constructional technique in a transistor, be it a small one inside a IC or a single "gate" in a device.

• nullpointerus - Saturday, April 1, 2006 - link

  I'd just like to put my vote in for "geeky electrical thingies."
  
  Seriously, does this matter to 99% of the readers?

• SonicIce - Friday, March 31, 2006 - link

  It's official! Joshua Buss of Anandtech does bad case wiring jobs!

• JoshuaBuss - Friday, March 31, 2006 - link

  Believe it or not, I don't do 'great' wiring jobs inside cases for testing as a matter of choice. Typically, users don't spend enough time routing cables neatly enough to stop all airflow blocking problems, thus I feel it's more accurate to actually leave a little cable clutter behind. Besides, if I spend much more time on it than the average user would, I'm not providing a good sense of how easy it is to do the cable management - I'd simply be showing off. The best way to give people a sense of how the case is laid out is to spend roughly the same amount of time in each case trying to clean them up a bit and see how far I get. With this case, I was able to get the majority of the mess out of the way with almost no effort, which is a testamanet to the ample space inside the HD-160.