Post by thread:[EE]: How to generate high voltage symetrical puls

Hi Piclist! I need to generate a low current high voltage (aprox. 80V), low current symetrical pulse train, using a 6V or 9V battery. I've made some experiences using a "inverted" power transformer and a signal generator, but get no pulses out (looking in a osciloscope). The ideia is to use a PIC to generate the pulses. I even did buy a low cost "training belt", to passive gymnastics and muscle toner, but all that i see when looking at the circuit board is a bunch of SMD transistors and resistors, and some caps (I've expected some inductors or coils, at last)... and the silicon controller chip sealed by a black plastic bubble. Someone can help me? Pointing the error or sugesting some schematics... Thanks to all! Dagmar -- http://www.piclist.com hint: To leave the PICList spam_OUTpiclist-unsubscribe-requestTakeThisOuTmitvma.mit.edu

Sounds like they've got a simple charge pump setup... "Dagmar C. Neto" wrote: {Quote hidden}> Hi Piclist! > I need to generate a low current high voltage (aprox. 80V), low > current symetrical pulse train, using a 6V or 9V battery. I've made some > experiences using a "inverted" power transformer and a signal generator, > but get no pulses out (looking in a osciloscope). The ideia is to use a PIC to > generate the pulses. > I even did buy a low cost "training belt", to passive gymnastics and > muscle toner, but all that i see when looking at the circuit board is a bunch > of SMD transistors and resistors, and some caps (I've expected some > inductors or coils, at last)... and the silicon controller chip sealed by a black > plastic bubble. > Someone can help me? Pointing the error or sugesting some > schematics... > > Thanks to all! > > Dagmar > > -- > http://www.piclist.com hint: To leave the PICList > .....piclist-unsubscribe-requestKILLspam@spam@mitvma.mit.edu -- ____________________________________________ Peter Donahue AMTS (Code Monkey) COM DEV R&D P (519) 622-2300 x2439 F (519) 622-8706 -- http://www.piclist.com hint: To leave the PICList piclist-unsubscribe-requestKILLspammitvma.mit.edu

> From: Dagmar C. Neto[SMTP:.....dagmarcnKILLspam.....RC.UNESP.BR] > Sent: Wednesday, December 17, 2003 12:39 PM > To: EraseMEPICLISTspam_OUTTakeThisOuTMITVMA.MIT.EDU > Subject: [EE]: How to generate high voltage symetrical pulses > Hi Piclist! > I need to generate a low current high voltage (aprox. 80V), low > current symetrical pulse train, using a 6V or 9V battery. I've made some > experiences using a "inverted" power transformer and a signal generator, > but get no pulses out (looking in a osciloscope). The ideia is to use a PIC to > generate the pulses. > I even did buy a low cost "training belt", to passive gymnastics and > muscle toner, but all that i see when looking at the circuit board is a bunch > of SMD transistors and resistors, and some caps (I've expected some > inductors or coils, at last)... and the silicon controller chip sealed by a black > plastic bubble. > Someone can help me? Pointing the error or sugesting some > schematics... You can go wrong in two different directions. First, if the pulses are too short, they can be lost in the stray capacitance of the transformer or inductor. This is especially a problem if you are using 60 Hz transformers with microsecond pulses. Even audio transformers must be used with care. Second, if the pulses are too long (wide), and you are using high frequency switching power supply transformers, the core of the magnetic device can saturate before the pulse ends. This will cause differentiation of the pulse. In other words, only the edges of the pulse will appear in the output. If you are using a variable frequency and width pulse generator, you should be able to find some output from whatever transformer you are using. Once you have that, you can go from there to find the limits of that transformer. If you then need to go higher in frequency, move on to audio and then switching transformers. If you need longer pulses, move in the opposite direction. John Power -- http://www.piclist.com hint: To leave the PICList piclist-unsubscribe-requestspam_OUTmitvma.mit.edu

Is that for a 40khz or 200kHz App? (common ultrasonic sensor - big capa) Sam Dagmar C. Neto Wrote Hi Piclist! I need to generate a low current high voltage (aprox. 80V), low current symetrical pulse train, using a 6V or 9V battery. I've made some experiences using a "inverted" power transformer and a signal generator, but get no pulses out (looking in a osciloscope). The ideia is to use a PIC to generate the pulses. I even did buy a low cost "training belt", to passive gymnastics and muscle toner, but all that i see when looking at the circuit board is a bunch of SMD transistors and resistors, and some caps (I've expected some inductors or coils, at last)... and the silicon controller chip sealed by a black plastic bubble. Someone can help me? Pointing the error or sugesting some schematics... Thanks to all! Dagmar -- http://www.piclist.com hint: To leave the PICList @spam@piclist-unsubscribe-requestKILLspammitvma.mit.edu

> I even did buy a low cost "training belt", to passive gymnastics > and muscle toner, but all that i see when looking at the circuit > board is a bunch of SMD transistors and resistors, and some Just as a BTW, I heard recently that these devices, when advertised as muscle toners, in that never-ending quest for perfect abs, were deemed a fraud and at least one company had to pay reparations I have a similar device which is more along the lines of a biofeed- back/physiotherapy machine, and is promoted as such, and that does have small transformers. Unloaded it can put out very short pulses at around 250VDC Have you considered a pulse transformer, the type used to fire xenon tubes, eg in strobe lights ? These take a HVDC pulse from the mains (240V here) and boost it to around 4kV. Assuming a 10:1 or more step-up you might get what you want from 6V, should get there with 12V The other option might be a switching regulator (IC or discrete) to get 80V and then chop it with a FET or transistor -- http://www.piclist.com hint: To leave the PICList KILLspampiclist-unsubscribe-requestKILLspammitvma.mit.edu

On Wednesday, Dec 17, 2003, at 13:07 US/Pacific, John N. Power wrote: >> I need to generate a low current high voltage (aprox. 80V), >> low >> current symetrical pulse train, using a 6V or 9V battery. There are driver chips aimed at powering EL backlights in this sort of output range (80V P-P, 400Hz, typically.) Try micrel, sipex, toko, or rogers corporation. These typically have a single inductor switchmode converter that generates about 40V, and an alternating output switch to make the 40V be 80V P-P AC. BillW -- http://www.piclist.com hint: To leave the PICList RemoveMEpiclist-unsubscribe-requestTakeThisOuTmitvma.mit.edu