the 4007 or what about that Piezo Loudenator kit ?
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| the 4007 (turned up the contrast on the laser marking) |
The CD4007 CMOS device is really quite a unique part. It can be connected to form three CMOS digital inverters but the p-channel and n-channel transistor of two of those inverters must have their leads connected externally to the chip. The result is that there are many applications where matched MOSFET transistors can be used other than just for digital inversion. There are a number of resources on the internet for the CD4007, here are a few:
https://www.ti.com/lit/gpn/cd4007ub data sheet
https://www.ti.com/product/CD4007UB ti page
https://www.electronicdesign.com/technologies/analog/article/21754492/whats-all-this-cd4007-stuff-anyhow Bob Pease article
https://wiki.analog.com/university/courses/electronics/electronics-lab-28 Analog Devices cd4007 page
http://schematicsforfree.com/files/Components/Semiconductors/ICs/CD4007%20Applications.pdf Ray Marston article
I used the CD4007 in the Piezo Loudenator kit.
The loudenator is a sort of low current amplifier that does a couple things. First, it allows a piezo sounder to be driven at a higher voltage (9 to 13.8 volts at least) than the usual 5 or 3 volts available from a microcontroller. And it also provides two outputs which are 180 degrees out of phase providing the fabled bridge output. Both of these allow a major increase in piezo sound volume while retaining the low standby current.
As can't quite be seen on the Piezo Loudenator schematic:
http://wb9kzy.com/loudensch.pdf
the n-channel transistor with the gate on pin 3 is the input to the circuit. It is pulled down to ground with the 1 megohm resistor to make sure that the input doesn't float. The source of the transistor on pin 4 is grounded. The drain on pin 5 is pulled up to the power supply voltage. The drain is also connected to pin 6 the input to the first inverter. The output of the first inverter on pins 13 & 8 is itself used to drive both the piezo AND the second inverter input on pin 10. The second inverter output on pin 12 is also connected to the second piezo lead.
The Loudenator really helps with circuits like a timer where the user may not be in the vicinity of the unit but still needs to hear it timeout. Also, timers are usually battery powered so the low standby power is nice.
How do those little piezos run at 1.5 volts manage to be so loud and obnoxious ? I think it's just a matter of driving the piezo at a resonance point (which are quite sharp). Most of my kits use the more pleasant 600 Hz frequency which even for a large piezo is way off resonance and thus not that loud.
Best Regards,
Chuck, WB9KZY
http://wb9kzy.com/ham.htm