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Cory D

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  1. I have received the 620R resistors....finally! I'll put this together and let you know the results...thanks
  2. Thank you for responding, Audioguru. So the ground on pin 7 and 8 should be separate to the source 0V? So if both grounds are separate, does the distance still have an effect with distortion and oscillation? Acoustical Feedback: I'm not sure what "Half-Duplex and Full-Duplex is. I'm not using speakerphones. Just 4Ohm-6w speakers. The speaker will only be on one end of the line. The speaker will be close to the handset, though. Another speaker will be approx. 10 to 12 feet away. I'm going to try this circuit (Below) to signal the amp from the phone line. I don't have the components yet to build or even try it. I have the 600 ohm TA and the diodes...but the 620K resistor is not in stock at any of the local electronic stores nor the CAP. Both are on order. Do you think this will work. I have 3 other schems that is used for this application. This one has less the components. Your input? BTW, Audioguru, thank you so much in the info on my Phone intercom system. The 300 ohm did the trick! Later, after you helped me get it going, I found a You Tube video showing how to make a 2-telephone intercom system for your house. Thanks again for the help. Now if I can get this amp and phone system to work....I'll be good to go!
  3. Hi all, haven't been in here for a while. I have built a 12VDC telephone intercom system that works fine. What I'm trying to achieve is connecting a amplifier to the phone service line so that the conversation can be heard without using the phone handheld. I have built a 6w amp from a schematic I downloaded using a TA7222AP amp chip (Schematic Below). I'm a little lost with this: For optimum performance input and output must be separately grounded. How can this be? What am I missing here? How can you have 2 different grounds? The input: I tried a 600ohm TA and tried hooking it direct...no go. What am I doing wrong here? Help! Suggestions...! Thanks, Cory D 6W amplifier using TA7222AP Description: Here is the circuit diagram of a 6W amplifier using the TA7222AP from Toshiba.TA7222AP is an excellent integrated audio amplifier which can deliver 5.8W to a 4 Ohms load at 12V supply voltage. The IC has very good features like, muting function, low distortion, high ripple rejection, short circuit protection, thermal shut down etc. This amplifier can be operated from 8 to 12V and this makes it ideal for car radio applications. Notes. The circuit can be assembled on a Vero board.Use 12V DC for powering the circuit.The IC must be heatsinked.Speaker can be a 4 ohms one.For optimum performance input and output must be separately grounded. Below is the amp schematic...the pic didn't download on the last post, sorry Cory D
  4. On the photo, I tried to use the INSERT OTHER MEDIA....is there a different way to attach a photo? I've been a member of this group before and its format has changed. I did, in the past, post photos. This is a really great Group...I have learned so much on practical electronics, and still learning! Audioguru, I did figure it out. The phones work fine...thank you! I also now understand that the RINGER circuit has to be on a separate current from the SIGNAL circuit. Having the resistor inline doesn't allow the other ringer components to function. I'm going to use the same power source (+12V) but split it into two currents. I have to re-design my circuit board in my CAD program. The 3 channel prototype circuit board I am currently using will have to be altered. My goal is a 13 channel system with operator panel. Again, thanks so much!
  5. I connected a 300 ohm resistor to the red wire and 300 ohm to the green wire, using an altered phone "Y", connected +12V (Red) and 0V (Green) and nothing. Tried to download a picture of how I have it rigged...wont let me.
  6. To to be clear I got this right...using a 12V battery, as long as I connect a 300 ohm resistor to the +12V power IN and a 300 ohm to the 0V (or negative) then connect both phones to the + and - sources...they will work. Do I have that right? You mentioned a "Relay Coil"....is that the same as the resistor? Going to give it a shot. Thanks audioguru
  7. Normal telephone line power runs around 224 K ohms @ -51 DC volts. The current, not sure how to measure it...but its around 1 amp...I guess, not sure. I'm trying to produce my own phone system with 12 call stations. I have watch a lot of youtube vides...but so far, nothings clear that I can get to work. I've been working on this close to a year! When you connect your tester on a hot phone line, it reads -51.9v and when you go off the hook, it drops to -8v. I have tried many things to get 2 phones to talk to no avail. Connecting a 12V Batt to 2 phones connected will turn on....but will not talk. Watching a youtube video show a guy doing just that and they worked! Perhaps new Wal-Mart $5 digital phones won't work? I'm a loss!
  8. I need to convert 12VDC solar power source to produce -51 VDC. I have searched on the Internet trying to find a DC to DC converter or the schematics to build one. Anyone know how to achieve this? Thanks
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