Class D amplifier (different kind :)

[pyrohaz1]

Hey guys, Class D amplifiers but a different form this kind, this question is more on OpAmps:

Right... I'm looking for an quad opamp that will best suit my job:

2 Opamps being used within a triangle wave generator operating at ~140Khz
1 Opamp as an inverting amplifier to amplify the incoming signal
1 Opamp as a comparator to create the PWM output

The output of the PWM op amp goes to a Source follower (?) mosfet stage etc etc.

What would be the best opamp? I managed to get about 60Khz out of a pair of 1458's...

I'm stuck on the Lm324 or the TL084 (power consumption when idle isn't a massive deal) Operating voltage will be ~32v +-1v

 

[Hero999]

You're lucky to get 60kHz from an LM1458, the LM324 is even slower - look at the datasheet.


Please post the schematic of the triangle wave generator.

I think you need two op-amps and two comparators. An op-amp is a very poor comparator, you'll need one with a huge slew rate and a massive bandwidth to produce PWM at 140kHz.

The LM393 and TL082 are probably what you need.

 

[pyrohaz1]

Thats perfect hero, thank you

Instead of creating a ne thread, i'd also like to ask: What is the difference of the TL series?
TL6xx
TL7xx
TL8xx

Is it just power consumption?

Cheers

 

[audioguru2]

Instead of creating a new thread, I'd also like to ask: What is the difference of the TL series?
TL6xx
TL7xx
TL8xx

Is it just power consumption?

There Are no opamps with those numbers.
Maybe you mean the TL06x, TL07x and TL08x?

Simply look on their datasheets:
1) The TL06x series has low supply current, a fairly low amount of gain, a low max output current and a fairly low maximum frequency of about 27kHz. They are very noisy.

2) The TL07x is a TL08x selected for low noise.

3) The TL07x and TL08x series has normal supply current, normal high gain, normal max output current and a good maximum frequency of about 100kHz.

Why don't you look at the class-D amplifier ICs that are made by a few manufacturers? 

 

[pyrohaz1]

Cheers audio, I did mean what you said, sorry!

To be honest... I would actually be prepared to use a class D IC but I find this area of electronics so interesting in how you can get such high efficiencies from such a well theoretically quite simple circuit and I am quite interested to learn through my own steps and errors. I mean, I know that you can listen to a class D IC to listen to the auditory quality but you don't really get to see the internal schematic of one of these chips (afaik) they are usually in a block diagram.

By doing it myself using the terminology, I can create my own designs and test them for auditory quality and such, plus the price of products: (eBay being my source here)
1x TA2024 Chip -

 

[audioguru2]

The TA2024 IC was made by Tripath. It and their other more powerful amplifier ICs were not very good. They went bankrupt over 3 years ago.

Some HongKong places still sell maybe a counterfeit one. It is also used in a few kits.

I don't know why American products are so expensive in Britain.

 

[Hero999]

I can buy a single TL082 and a single LM393 for 53p and 28p respectively from RS. Components here aren't expensive, unless you shop at Maplins.
http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=0304217
http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=5343009

I don't know about the TA2024 but RS sell class D amplifier ICs for less than half the price.

http://uk.rs-online.com/web/search/searchBrowseAction.html?method=retrieveTfg&Nr=AND%28avl%3Auk%2CsearchDiscon_uk%3AN%29&N=4294611853+4294608190&Ns=stockPolicy_uk%7C1%7C%7Cnew_uk%7C1&No=0