Home |
Search |
Today's Posts |
|
Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
Reply |
|
LinkBack | Thread Tools | Display Modes |
#1
Posted to sci.electronics.design, sci.electronics.repair, alt.engineering.electrical
|
|||
|
|||
Weird piezo driver
http://imgur.com/Trvs5mk
This is a beeper piezo in a Fluke 117 DMM which quite beeping. Scoped the piezos pads and... nothing. An inverter (from the CD4069) is connected across the piezo. Guess I dont understand anything about driving piezos. Is this a standard practice? Cheers. |
#2
Posted to sci.electronics.design,sci.electronics.repair,alt.engineering.electrical
|
|||
|
|||
Weird piezo driver
On 16/05/2016 07:36, DaveC wrote:
http://imgur.com/Trvs5mk This is a beeper piezo in a Fluke 117 DMM which quite beeping. Scoped the piezos pads and... nothing. An inverter (from the CD4069) is connected across the piezo. Guess I dont understand anything about driving piezos. Is this a standard practice? Cheers. My Fluke 77, will beep when the battery is low but not low enough to trigger the LCD legend, presumably drift over time |
#3
Posted to sci.electronics.design,sci.electronics.repair,alt.engineering.electrical
|
|||
|
|||
Weird piezo driver
On 16/05/16 16:36, DaveC wrote:
This is a beeper piezo in a Fluke 117 DMM which quite beeping. Scoped the piezos pads and... nothing. Did you mean that "it quit beeping"? If so, you aren't going to hear anything. An inverter (from the CD4069) is connected across the piezo. Guess I dont understand anything about driving piezos. The Fluke should be producing a square wave, say 1KHz, across the piezo. The piezo itself looks like a mid-sized capacitor; you won't get any DC resistance reading through it. They are extremely high resistance devices. If you touch 9v to either side of the piezo, you should hear it click, and click again when you disconnect. The Fluke does that too, but fast. |
#4
Posted to sci.electronics.design,sci.electronics.repair,alt.engineering.electrical
|
|||
|
|||
Weird piezo driver
On 16.5.16 09:36, DaveC wrote:
http://imgur.com/Trvs5mk This is a beeper piezo in a Fluke 117 DMM which quite beeping. Scoped the piezos pads and... nothing. An inverter (from the CD4069) is connected across the piezo. Guess I dont understand anything about driving piezos. Is this a standard practice? Cheers. You'll get AC drive when you drive one side with a logic signal and the other side with the same signal inverted. -- -TV |
#5
Posted to sci.electronics.design,sci.electronics.repair,alt.engineering.electrical
|
|||
|
|||
Weird piezo driver
On Sun, 15 May 2016 23:36:38 -0700, the renowned DaveC
wrote: http://imgur.com/Trvs5mk This is a beeper piezo in a Fluke 117 DMM which quite beeping. Scoped the piezos pads and... nothing. An inverter (from the CD4069) is connected across the piezo. Guess I dont understand anything about driving piezos. Is this a standard practice? Cheers. If you put an inverter across the piezo you get double the supply voltage drive - push-pull. Not uncommon. Typically you'd drive each side with two paralleled inverters and use another inverter to invert the input to one pair. The piezo element looks something like a ceramic capacitor electrically. A series capacitor is often used. --sp -- Best regards, Spehro Pefhany Amazon link for AoE 3rd Edition: http://tinyurl.com/ntrpwu8 |
#6
Posted to sci.electronics.design, sci.electronics.repair, alt.engineering.electrical
|
|||
|
|||
Weird piezo driver
On 16 May 2016, Clifford Heath wrote
Did you mean that "it quit beeping"? Yes, quit beeping. Thanks. |
#7
Posted to sci.electronics.design,sci.electronics.repair,alt.engineering.electrical
|
|||
|
|||
Weird piezo driver
In article
, DaveC wrote: http://imgur.com/Trvs5mk This is a beeper piezo in a Fluke 117 DMM which quite beeping. Scoped the piezos pads and... nothing. An inverter (from the CD4069) is connected across the piezo. Guess I dont understand anything about driving piezos. Is this a standard practice? Cheers. Piezo drivers have a high impedance so they need high voltages. One side of that piezo element is driven with the signal source and the other side is driven with the inverted signal. That doubles the drive voltage so it's loud enough to hear. -- I will not see posts from astraweb, theremailer, dizum, or google because they host Usenet flooders. |
Reply |
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
Lanyard for Makita 10.8V drill/driver & impact driver? | UK diy | |||
Impact driver Drill/Driver Kits | Woodworking | |||
Piezo capacitance | Electronic Schematics | |||
Piezo igniter output waveform - piezo sparker.pdf | Electronic Schematics | |||
drill-driver vs magazine driver 200 budget | UK diy |