Search found 2219 matches

by Robert Reed
Wed May 18, 2005 4:26 pm
Forum: General Discussion
Topic: Sound Power
Replies: 25
Views: 4062

Re: Sound Power

jwax: Correct - every doubling of power will get you 3DB's. I had considered a flock of cheap piezos, but was warned of possible acoustic cancellations, Not familiar enough with this subject to make any intelligent decisions. It's like Rossana Anna Danna says-Its always something. Have checked out r...
by Robert Reed
Tue May 17, 2005 8:53 pm
Forum: General Discussion
Topic: WATT-HOUR METER Table Lamp
Replies: 7
Views: 1175

Re: WATT-HOUR METER Table Lamp

I salvaged ,built and own one of these lamps. I believe the meter is circa 1960 which I aquired in the 90's when I worked radio comm.& microwave relay for the local power company. Mine spins at approx. 20 rpm and this seems like a good speed also light years ahead of what a 60 watt load would normal...
by Robert Reed
Tue May 17, 2005 9:09 am
Forum: General Discussion
Topic: Sound Power
Replies: 25
Views: 4062

Re: Sound Power

jwax: Thanks again for another informative web site. ezpcb: There are a number of ways to driive the end device (tweeter?),which are not to difficult to construct. However my big hangup so far has been the end device. Getting a lot of mixed signals on piezo information.The most credible device (sugg...
by Robert Reed
Mon May 16, 2005 8:23 pm
Forum: General Discussion
Topic: Add DC bias to sinusoidal signal
Replies: 13
Views: 4134

Re: Add DC bias to sinusoidal signal

Not sure what the battery is for. Cannot see detail on sine graph to make it out. So I'll take a wild shot at it any way. Could you bias the circuit like most single supplied op amps,that is resistively split the supply and return both inputs to that point. They would be capacitively coupled of cour...
by Robert Reed
Sun May 15, 2005 8:55 pm
Forum: General Discussion
Topic: Sound Power
Replies: 25
Views: 4062

Re: Sound Power

Thank you Jwax for your web site-will check it out. Have been trying to get detailed info on tweeter power ratings and I guess I'll try the manufacturers. Hopefully end up with their engineering Dept. I calculate that at 150' distance I would need 125 DB at the source to end up with 90 DB at stated ...
by Robert Reed
Sat May 14, 2005 10:11 pm
Forum: General Discussion
Topic: Terri's Law
Replies: 3
Views: 799

Re: Terri's Law

Sea clams can weigh up to 500 pounds
by Robert Reed
Fri May 13, 2005 5:30 pm
Forum: General Discussion
Topic: Capacitance measurement needed
Replies: 4
Views: 894

Re: Capacitance measurement needed

Not enough info!! What is your DEVICE And What are you trying to CONTROL.
by Robert Reed
Fri May 13, 2005 12:00 pm
Forum: General Discussion
Topic: High frequency to voltage converter
Replies: 10
Views: 1837

Re: High frequency to voltage converter

One diode , one resitor, one capacitor. Arrange as an RF detector used in test equipment probes. Feed a Transistor Ampl, with this and pick off the DC you desire. Cant give exact values without knowing more parameters, but for starters a 1N914 seriesed into a1000 PF to ground then feed transistor ba...
by Robert Reed
Fri May 13, 2005 11:44 am
Forum: General Discussion
Topic: Sound Power
Replies: 25
Views: 4062

Re: Sound Power

Thanks all for replys. As to the 120 Watt Amp and two piezos , what was the rms voltage output? My problem has been a high enough driving voltage to get max power into these tweeters (example--75 watt tweeter & 120 ohm Z, would require 95 volts rms according to ohms law E sq./120) Or are the manufac...
by Robert Reed
Thu May 12, 2005 9:06 pm
Forum: General Discussion
Topic: Sound Power
Replies: 25
Views: 4062

Sound Power

I need a high power , high frequency sound source. 15 to 20 Khz & 120 db,150 db? My original attempt was a 50 Watt amp (@8 0hm) Driving a pair of Piezo horn tweeters. Coulnb't get the sound power needed as I later discovered these have an impedance of approx. 120 ohms.Now I am thinking of switching ...
by Robert Reed
Tue May 10, 2005 5:32 pm
Forum: General Discussion
Topic: Driving a relay from a 3V AC signal
Replies: 8
Views: 1715

Re: Driving a relay from a 3V AC signal

OOPS--May have made too many assumptions, When you say 3VAC--are you referring to 60 Hz line or other. If you are driving an opto device prior to the relay coil. what is input Z. If hi enough, the before mentioned circuit driving CD4528/38 (retrig. one shot) with period 20 milliseconds would do the ...
by Robert Reed
Tue May 10, 2005 4:42 pm
Forum: General Discussion
Topic: Driving a relay from a 3V AC signal
Replies: 8
Views: 1715

Re: Driving a relay from a 3V AC signal

3VAC--RMS? This would be 4.3 Volts Peak .Just clamp the negative portion to ground with a diode thru 10K resistor. This will be enough to drive 5V CMOS logic. Assuming that your 3VAC is from lo freq. source.
by Robert Reed
Thu Mar 31, 2005 9:09 pm
Forum: General Discussion
Topic: Can nomeone explain this to me: current(AC vs DC)
Replies: 21
Views: 3823

Re: Can nomeone explain this to me: current(AC vs DC)

The lamp setup like you descibe, many times use switching supplies that actually out put hi-freqency AC (5-10 Khz).This would give screwy readings in either AC or DC on your lo-frquency meter.
by Robert Reed
Wed Mar 30, 2005 8:31 pm
Forum: General Discussion
Topic: missing parts list Nuts/Volts April
Replies: 2
Views: 648

Re: missing parts list Nuts/Volts April

Editors mistakenly omitted the parts list.Also they left out Fig. #2 which shows board layout. Should be posted on their website as of now.