supercapacitors
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From: tschoepflin@gmail.com on 16 Aug 2006 12:00 Does anyone have experience with supercapacitors? What's the best way to learn more about them and what they're useful for? Any good web links with design examples? We have a 1 kW transmitter for ultrasound that uses 12 electrolytic capacitors (2200uF each) in a bank, for 26.4 mF total capacitance. The ESR is very low so our system responds very well when transmitting pings (lengths ranging 0.1-1.0 ms). The caps are buffering a 48V power rail. I've thought about trying to scale the power rail down to 12 V and beefing up the transformer by a factor of 4. Has anyone used a supercapacitor in a transmitter? Thanks for the help. -Todd
From: PeteS on 16 Aug 2006 12:19 tschoepflin(a)gmail.com wrote: > Does anyone have experience with supercapacitors? What's the best way > to learn more about them and what they're useful for? Any good web > links with design examples? > > We have a 1 kW transmitter for ultrasound that uses 12 electrolytic > capacitors (2200uF each) in a bank, for 26.4 mF total capacitance. The > ESR is very low so our system responds very well when transmitting > pings (lengths ranging 0.1-1.0 ms). The caps are buffering a 48V power > rail. I've thought about trying to scale the power rail down to 12 V > and beefing up the transformer by a factor of 4. > > Has anyone used a supercapacitor in a transmitter? > Thanks for the help. > -Todd Most supercaps I used (some time ago now) have rather high ESR (in the order of tens to even hundreds of ohms), to say nothing of the fact that most of them are very low voltage devices. I haven't used them recently, though, so things may have changed. Cheers PeteS
From: martin griffith on 16 Aug 2006 12:37 On 16 Aug 2006 09:00:36 -0700, in sci.electronics.design "tschoepflin(a)gmail.com" <tschoepflin(a)gmail.com> wrote: >Does anyone have experience with supercapacitors? What's the best way >to learn more about them and what they're useful for? Any good web >links with design examples? > >We have a 1 kW transmitter for ultrasound that uses 12 electrolytic >capacitors (2200uF each) in a bank, for 26.4 mF total capacitance. The >ESR is very low so our system responds very well when transmitting >pings (lengths ranging 0.1-1.0 ms). The caps are buffering a 48V power >rail. I've thought about trying to scale the power rail down to 12 V >and beefing up the transformer by a factor of 4. > >Has anyone used a supercapacitor in a transmitter? >Thanks for the help. >-Todd I'd go they otherway and use a 12V lead acid battery array martin
From: Joerg on 16 Aug 2006 12:56 Hello Todd, > Does anyone have experience with supercapacitors? What's the best way > to learn more about them and what they're useful for? Any good web > links with design examples? > > We have a 1 kW transmitter for ultrasound that uses 12 electrolytic > capacitors (2200uF each) in a bank, for 26.4 mF total capacitance. The > ESR is very low so our system responds very well when transmitting > pings (lengths ranging 0.1-1.0 ms). The caps are buffering a 48V power > rail. I've thought about trying to scale the power rail down to 12 V > and beefing up the transformer by a factor of 4. > I wouldn't really call that a super capacitor. A few hundred uF or more per channel isn't that unusual. In my ultrasound designs the most important aspect was where the peak current would be coming from. This data plus ESR values is in the data sheets and if not you have to obtain it. > Has anyone used a supercapacitor in a transmitter? Real super caps are in the Farad capacitance range, more like short-term backup supplies. They come in various flavors. As Pete said they can be high in ESR, for example if their market is RAM backup. You would need the ones that are marketed into the short-term power supply sector. A kilowatt is nothing to sneeze at. Especially if it is Doppler and more than just one short pulse, be careful. I have seen electrolytics explode with gusto when exceeding the max ripple rate. A short pulse can be cushioned off with several high quality smaller caps but long pulse trains really can't. -- Regards, Joerg http://www.analogconsultants.com
From: default on 16 Aug 2006 15:11
On 16 Aug 2006 09:00:36 -0700, "tschoepflin(a)gmail.com" <tschoepflin(a)gmail.com> wrote: >Does anyone have experience with supercapacitors? What's the best way >to learn more about them and what they're useful for? Any good web >links with design examples? > >We have a 1 kW transmitter for ultrasound that uses 12 electrolytic >capacitors (2200uF each) in a bank, for 26.4 mF total capacitance. The >ESR is very low so our system responds very well when transmitting >pings (lengths ranging 0.1-1.0 ms). The caps are buffering a 48V power >rail. I've thought about trying to scale the power rail down to 12 V >and beefing up the transformer by a factor of 4. > >Has anyone used a supercapacitor in a transmitter? >Thanks for the help. >-Todd Check out Maxwell Technologies they make a super cap that is a cross between a lead acid battery and high capacity capacitor - very low ESR and can deliver 100's of amps http://www.maxwell.com/ultracapacitors/index.html ----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |