Buzzer

[KMoffett]

Great! ....

But, the problem you are going to have with the cellphone batteries is that they are lithium-ion. These require a "very" special charger. Often the charger circuit is in the cellphone, not in the wall wart.

But after a quick Googel: https://www.amazon.com/s/?ie=UTF8&keywords=bt51+charger&tag=googhydr-20&index=aps&hvadid=14584877395&hvpos=1t1&hvexid=&hvnetw=g&hvrand=203986430945789132&hvpone=&hvptwo=&hvqmt=e&ref=pd_sl_3kpnb3y24r_e

Ken

 

[rthuey]

oh i still have the phones. so i will just drop the battery back in one of them to charge as needed.

 

[KMoffett]

If that works for you.

Another "but" here...your circuit has no way of determining if or when the Lithium ion battery is being over-discharged, unlike the phone.

Ken

 

[rthuey]

thanks to the help from KMoffett. i have had this working on and off a breadboard (initial mock up). i was going to try and work a motion sensor into the circuit so i re-breadboarded the circuit.



after setting up the circuit this am on the learning lab. it straight up did not work. checking the voltage supplies on the lab i was getting nothing. i pulled the batteries (6 aa). individually they showed 1.3v. i went to put them back in and realized that 3 of the spring terminals were shorter than the others. further examination showed that the bases around the springs had melted. i don't believe it was this morning that it happened. last week i was working on a different circuit on the lab and was not getting the responses i was expecting. i think this is when i must have shorted something to cause this.



i left circuit on the lab. i left out the 6 aa batteries and jumpered the BT51cell phone battery i have been using directly to the circuit on the lab. the circuit is active when i connect the battery, to the point where the vibrator comes on and stays on.

i did some troubleshooting but i am also wondering if the breadboard itself can be compromised from the assumed pre mentioned short incident.

troubleshooting
remove power supply to VIN jumper completely and the vibrator speeds up.
remove the 470 resistor completely and the vibrator stops.
remove the 10k resistor completely and no change, the vibrator continues.
remove the diode completely and no change, the vibrator continues.

voltages with complete circuit
supply voltage 4.19v
vin 4.19v
out 2.84v
e 4.19v
b 3.61v
c 3.97v

voltages with vibrator removed from circuit
supply voltage 4.18v
vin 4.18v
out 3.38v
e 4.18v
b 3.55v
c 1.35v

any thoughts?

 

[rthuey]

oy vey. took all day but i got it.

i had mixed the feeds to VIN and OUT going to the proximity sensor. :barf

 

[rthuey]

connection question. when breadboarding the circuit above i connected the end of R1, R2 and Q1 on the same row that was interconnected. the circuit works.

is the correct way to connect it to run R1 and R2 to one interconnected row and then jumper that row to a separate row that has Q1 on it?

on a different section of the breadboard

the next circuit i am trying to integrate has ends of D2, C2, R2 and Q1 that are on a row that is interconnected. the circuit does not work.

is the correct way to connect it to run D2 and C2 to one row. Jumper it to another row the has R2 and Q1 on it?

 

[KMoffett]

....is the correct way to connect it to run R1 and R2 to one interconnected row and then jumper that row to a separate row that has Q1 on it?

on a different section of the breadboard

the next circuit i am trying to integrate has ends of D2, C2, R2 and Q1 that are on a row that is interconnected. the circuit does not work.

is the correct way to connect it to run D2 and C2 to one row. Jumper it to another row the has R2 and Q1 on it?

Any leads that are connected together can all be connected on one row (up to 5 on most boards) or connected on rows that are jumpered together. There in no "right" way.

One problem that I've seen with boards at our labs, is that after long use, contacts can fatigue and can make poor contact.

But 90% of the time the problems are due to not wiring the circuit correctly. Check and recheck. A good practice is the first take a DMM and check to see if you have the voltages that you would expect in the leads of components.

Ken

 

[rthuey]

so because of the meltdown on the learning lab. i went out and purchased a new breadboard and power source.

next step is to integrate a motion circuit into the buzzer circuit. the SQ-SEN-200 is an omnidirectional tilt and vibration sensor which i would like to supply the Vin voltage to the buzzer circuit when activated via what is marked as V Out on the motion circuit. i have started with a sample circuit from the SQ-SEN-200's website. the one on the left uses a NMOS 2N7000. the one on the right uses a PMOS ZVP3306A. the only piece that changes in the circuit is Q1. besides labeling all the parts, each diagram lists the voltages i am seeing at the same four points. the top measurement is with no motion and the lower is when there is motion. most of the voltage readings travel, as in they don't stay at one voltage. guessing this is because of the caps.

the manufacturer has helped some and suggested that i should go from the NMOS to the PMOS. because as drawn the schematic should be giving a low signal. i am trying for 3.5v - 4v at V Out on the motion circuit. they said "i could also invert the signal by using a PMOS instead of an NMOS. because a PMOS conducts with the gate at 0V the voltage rails of C2 and R2 would have to be swapped." i am unclear what they mean by swapping the voltage rails. a resistor has no polarity so they can't mean just flipping them around.

thoughts on their circuits or ideals for any other way to do this? simpler would be nicer.

 

[KMoffett]

In your second schematic you are using a NMOS symbol in a Common-source for a PMOS transistor. Were your measurements in a simulator?

Ken

 

[rthuey]

no not simulator. yes the PMOS (second) schematic was only relabeled from the original NMOS schematic, i did not change the picture in the circuit.

by swapping the voltage rails, they wanted me to take C2 and R2 from going to ground to going to power. Changing R2 into a pull up instead of a pull down. I did this and tried C2 both directions and still get 0v at V Out with or without motion. Will take all four readings after i top off the batteries.

 

[rthuey]

i am getting closer. i have a more acceptable voltage at the V_Out. Although it is there whether or not there is motion detected.

okay i have some updated schematics. the icon of the MOSFET is the same in all, Q1, the leads are properly labeled as to whether they are Drain, Source or Gate though. still breadboarding not simulating.

There are four reading points labeled A,B,C and D on each. The bottom readings were taken first and are while the SQ-SEN-200 itself being tapped on for about 15 seconds. The top readings were taken after stopping tapping and observing the meter for several seconds.

Bottom readings of A and B are constantly fluxing on both circuits. No particular pattern.
Top readings of B on both of the circuits appear to charge up then discharge continuously.
Top readings of C drain down. Bottom readings of C fluctuate with no particular pattern.

My order of progression through the MOSFET has been from
2N7000 3v @ 1mA Gate Source Voltage
ZVP3306A 3.5v @ 1mA Gate Source Voltage
ZVP3306A v2 3.5v @ 1mA Gate Source Voltage
ZVP4424A 2v @ 1mA Gate Source Voltage


I can get a lower Gate Source Voltage by changing package to something like this ZXMP6A17E6TA to get me down to 1v @ 250 microA. I am not sure if i should be looking at lowering that more or something else.

 

[KMoffett]

D2 in your circuits prevents the circuit from working.
Why have you not used the AC coupled circuit on page 2: https://signalquest.com/download/SQ-SEN-200%20App%20Circuits.pdf The FET on the input of the microcontroller in that circuit is an NMOS. Replace it with your N-MOSFET, grounding the source, and placing your buzzer between the drain and the + supply.

Ken