CALAHAN

Audioguru, No it's a 10k alright. I took it apart last night to try both the 3.3k and 10k. Bruce

The volume/switch pot is round and there is no damage on it. I have the device wired as you have it already. All to pin 7. Bruce

I changed the resistor from pin 4 to 5 with a 10k instead of the 3.3k because I needed the extra volume. I tried the with both value resistors tonight, and both are the same - all or nothing. Bruce

I changed out the main 3.3k resistor at pin 4 to 5 to get a bit more volume on the whole unit per your suggestions prior. Could this be the issue? Bruce

Audioguru, Now that am using this amp circuit, I have lost my volume pot on the FRS. I get all, or nothing. The wipe of the resistance has been cut to immediate if you know what I mean. As I had stated early on, this FRS uses a resistor pot with thumb wheel. Any fixes? I am also wondering how this problem will lay out when I use the circuit on an FRS with digital volume control instead of analog. Bruce

Audioguru, I inserted the new amplifier into the communicator tonight. All works great. I tweaked the resistors a bit to mix the volume levels as I wanted and no issues. Thank you for you time and patience on this - and thank you for helping me realize this childhood dream of having an actual "working" Star Trek communicator. Now I have one and will be making more. I'll be the talk of the campground. Bruce P.S. now to tweak the antenna a bit more. I picked up a helical 2.5" duck stubby tuned to my frequency range, and now to figure out how to hack this thing to fit in my shells and create a proper ground plane. But I have had a bit of experience in this already.

Audioguru, Something happened last night to the breadboard setup. It worked initially, but as soon as I connected the FRS, and tried to change resistor values out, the thing quit working. I put the multi-tester on the power input wire for the IC chip and it showed good, but putting the probe on the actual no. 6 IC contact showed no power. Something must have been grounding. Also, I tried direct grounding pins 2 and 3, and all it gave me was reduced volume. Puttingin the 1.0 uf resisters caused the thing to squeel. I changed the whole assembly to different holes in the board, and it worked, however, it seems that I needed to use the two diodes to control the distortion of the sound effects circuit. I also experienced the clicking I was speaking about earlier which occures if the sound effects is hooked up to the breadboard and the FRS goes into power saving mode. The only way to get rid of it was to put in the two 1. capacitors, and this time the squeeling did not happen, and the whole circuit now works what appears to be perfectly. Something went wrong on the breadboard and I do not know what. Tonight I will attempt to solder the amplifier circuit together for actual use in the communicator. I will advise by the end of the weekend it this was a success. It looks as though there willbe no skimping on the different components after all. If this works, I will build one of these for all of my future FRS communicator projects, unless of course I can find room for two seperate speakers. I will always need to power both on one power supply. Are you any good with antennas? Bruce

Audioguru, I'll look through some of the junk in garage for a capacitor that is smaller at 10uf, but will use the one I have if needed. There is not an issue with it working, it's just too big. As for pins 2 and 3, I tried them with capacitors, and with direct connections to gound. Either way, the sound was heavily effected. When removing them altogether, the sound was fine with no connection to the pins at all. Since I have the zeners here, I'll use them - if needed. The different resistor will be tried first. Bruce

Audioguru, I don't know how to turn on the "reply with quote" function with this message board. When I stated returning to the 10uf capacitor, I was refering to the fact that I have removed this from your schematic to save space and there was no noticable sound difference. Now that you state that is is needed for when the battieres start to die down, I will return it. I'm sure someone out there sells a flat ceramic disk 10uf capacitor, but I wonder how big the thing is. The little 10uf culinder is not that bad, so I'll find the room. I take it there is no issues with me removing the ground connections of of pins 2 and 3? When I used them my sound was messed up with or without the capacitors. Tonight I will just try and change the input resistor for the sound effects end to try and turn the volume down so it won't distort. If that does not work with the resistors I have on hand here, I will use the diodes. I do think I have a few of the glass Zener diodes here. I also have a few 1N4001 Micro 1A Diodes Here is the RadioShack page on them: http://www.radioshack.com/product/index.jsp?productId=2036268&cp=&sr=1&origkw=diode&kw=diode&parentPage=search I have the 1N4003 also which I think is the same as the 4001 but just can handle more input voltage. I have two IN4733A Zeners also. Bruce

Audioguru, I shoudl use those small black colored silicone diodes witht he white band from Radioshack? Out of curiosity, which was does the band face in the circuit? And - for the heck of it, what does the supply bypass capacitor look like? Are you talking about returning the 10uf capacitor back? The issues with that is the cylinder capacitor. If I could find a cermaic dick capacitor instead, I could find room for that. Bruce

Audioguru, Well my friend, it worked. I am very pleased. After I knew it would work, I started eliminating some of those pieces to see what could be done away with without changing the sound ( I need space). I was able to eliminate the two grounds completely off pins 2 and 3. And - I was able to eliminate the 100 uf capacitor to ground off of pin 5 altogether. No change in sound quality. Here is one issue I am having. I reduced the resistor as you stated, which did in fact lower the volume to keep the sound effects from distortion, however, it also lowers the FRS peak volume too, and I need the FRS volume. As I had stated earlier, the sound effects chip really actually uses 3 volts, but I have been running it on the 4.5 volts and it has not fried. It is even louder as I wanted. With the amp IC added, it is too loud now and distorts the speaker. I took a 69 ohm resistor and placed it between the power of the sound effects and the positive power rail. It reduced the volume to where I wanted it and cleaned up the distortion, however, there is a constant click present. I tried to add different values of resistor, and as I increased the value, the clicking stopped, but the volume also became low and unstable. Any ideas here? Thanks, Bruce

Audioguru, After looking at youir schematic again, I kind of figured you would say that. The MC34119 only needs the one wire out of the FRS, where I had both - one to the capacitor and the other to ground. I'll reduce that resister also in my trials tonight. Can 1/4 watt resistors work? I need the smaller size to conserve space. Bruce

Audioguru, I can't solder wires to parts of the FRS circuit board. That would be very risky, even if I could find those locations you pointed out on it. As for the earbud, I plugged it into the headphone jack, the other end was stripped and I put alligator clips on the ends to the breadboard. You mean to tell me that if I cross those two wires I stripped, the whole thing is blown? I was under the assumption that one wire from the earbud was hot and the other ground. Is this not correct? there is nothing touching that one contact coming off the positive battery terminal in that jack array. I didn't do anything to the FRS circuit board. In fact, I took an unaltered earbud and snapped it in, and the sound does come through, so I doubt anything on the FRS is fried. I will solder jump wires off the earbud stripped wires rather then use alligator clips and try that. The ear bud is very small, and the wires a mere few strands. I'll do this to ensure proper connection. It is either the connection or the breadboard. Is there anyway of turning the volume down a bit with this chip? As I had stated, I really didn't need the exra volume, and it is at near distortion at this point. Bruce Bruce

Audioguru, Well I breadboarded it tonight. I wired it up to the values as you have it. I tried a few variables with the capacitors - both the 100 and 10 uf. I also used two 1.0 ufs instead of the 1.0 and 5.0 at pin 2 and 3 to ground. I found that the capacitors at these pins either diminished the volume or caused inconsistent sound. I removed them all together and left those two pins unconnected and it worked. It is at the brink of distortion but acceptable. These are regular alkalines by the way. I will be using AAA lithiums in the final version because I need to bring the amperage somewhat back up as I replaced the 3 AA for these 3 AAA's. I wonder what effect those will have. I have a pristine FRS model of the one I hacked for the communicator, so I used this for the breadboard. I did exactly as you indicated. I took one of those "earbuds" and put into the headphone jack, cut the earpiece end of it off, stripped the wires, ran one to ground and the other to the breadboard as indicated and found that there is no sound coming through the speaker (I used a second FRS and created sound to be able to hear of course). I can hear the other FRS through the earpiece (I have two of those also), but the spliced one is not amplifying through the chip. Other then that, all is working. Now what? Bruce

Audioguru, Just an observation, but the line off the headphone lead you have me connected to alreay is being fed through a 3.3k and what appears to be a capacitor on the circuit board. I'll have to figure out which solder pont is which on that headphone jack where it is connected to the board. As I said, th ejack itself has been destroyed and used a mount for the Xmit switch. Bruce

Audioguru, The 3.3k ohms can be replaced with 10k ohms? Bruce

Audioguru, I have some headphone cable around the house, but as far as I know, it is not shielded. It is two wire or three wire. These connections are about 5 cm or just over (but not by much), so I'll use regular wire. O.K. on the rest I'll buy the 3.3k (I have the 10's already) resistors and give it a shot over this week and let you know. Do I realy need those capacitors at the other pins? The 1.0, 5.0 etc? Thanks, Bruce

Audioguru, You stated" "Of course one or both amplifiers will fry if you connect them to the same speaker and the same battery. Their output DC voltages are completely different and all the battery current will flow between them." What I sated is that I have both runing to a common speaker, but are running off of "seperate" powere sources, not the same. Will they still fry? They have worked good so far. As for this new schamtic. I'm confused. I'm supposed to hack apart shielded audio wire? I don't have room for that stuff. Why I can't I use regular wire? Are you telling me to find audio wire that is rated at 8 ohms? I have to tap into the FRS's tiny printed circuit board looking for that line off the ground before a resistor? You show the ground off the FRS negative connected to the shielding, but where does the center of the shielded wire come off of? I hope it is not the headphone jack. The headphone jack on the FRS board has been destroyed and is used for the mount of the Xmit switch. I need to be able to hook this up off the hanging FRS speaker wires. What number pin is the P- on the MC34119? Thank You, Bruce

Audioguru, So I put an 8 ohm (can I used 10 ohm?) resistor at the end of the speaker + of the sound effects chip and connect it right to the 0.1 capacitor, which is connected to the 3.3k resistor right? We don't use the 10k ohm anymore? Here is the best I can do for the FRS schematic in way of clarity. I cropped the schematic for the speaker output circuit. Also, can you look at that pot switch and tell me what value it is if I need to order more? 1k, 5, 10k... I need to ask this again: Currently my project uses the same speaker for the FRS and the sound effects, but different power sources. Will this still eventually fry one of the two amps? I'll have to go out and buy these components or orer them on-line, as these are not common Radio Shack stock. 1/4 watt resistors o.k.? Thanks, Bruce

Audioguru, Thanks, but what kind of capacitor, and where does it go? I put an 8 ohm resistor at the end of the speaker +, then a ? capacitor, then a 10k ohm resistor, then into pin 4 of the MC34119. For the FRS, speaker +, 8 ohm resistor, ? capacitor, 10k ohm resistor, MC34119. Both the FRS and the effects can be combined at pin 4 of the MC34119? all grounds to the ground rail. Currently my project uses the same speaker for the FRS and the sound effects, but different power sources. Will this still eventually fry one of the two amps? Thanks, Bruce

Audioguru, Sorry for my inability to create a proper schematic, but this is basically a trace of what I have for this toy sound effects chip. The colored boxes (other then black) are for wires which led to switches and LEDs for other sound effects which I will not be using. I clipped those wires. P+ and P- are the power lines SW indicates switch pads and you can see the corresponding negative pads that surround them. The diaphram covers were removed. I used SWR in the term list which is wrong. It should be "SW". 473 CAP is a capaciter with 473 written on it. and 100uf is of course one of those cylinder capaciters. the rest is self explanatory. Thanks for taking the time on this one. Don't forget that I need to power this, any Op Amp needed, and the FRS off of one 4.5 volt battery bank. Bruce

Audioguru, I decided to take the time and read through the internet, and once again purchase more components to try what you suggested. What you are saying is that the + outputs of these speaker wires need to be brought down to line level and then fed into an amp to bring the volume back up again. Bringing them down to line level with resistors creates a mixing circuit where both circuits are separated from each other from shorting. I tried putting a 10k ohm resistor in the + end of the speaker outs of these two devices, with the - going to ground and even tried a more complex (using one 10k and one 1k resister to create a split) idea where the outputs of these two devices were to be brought down to line level. I then tried the LM386, and the MC34119, and even played with an TLO82. None of these configurations worked - no sound - nothing. I tried different values of resistors, capacitors, removing capacitors, and resistors etc... The TLO sounded promising, but there are no schematics that I could find to wire two circuits, at either line level or amplified output voltage, into this thing and them to a single speaker. I did searches for hours on that thing, and found nothing. The data sheet schematics on it are no help. Speaking just of the sound effects circuit, I used the schematics you drew up for me with the MC34119 months ago, and did get a bit of sound out of it, but too low in volume. I even tried putting a 10 ohm resistor at the ground of the circuit's main, and it helped a bit but really only cleaned the sound up a bit, but no added volume. When I tried adding the FRS to it, the radio would not light up. They seems to fight for power (remember that all of these devices are wired to the breadboard of the 4.5 volt power rail). I tried a 10 ohm resistor on the sound effects circuit negative along the FRS, and still nothing. These IC's, the sound effects circuit, and FRS have to be powered off the same 4.5 volt bank of AAA's. None of the configurations work. I tried everything I could find on the internet. I would be willing to pay you, or someone else if I could get a working schematic to work for this project. Give me a quote privately if needed. As it stands now, my next build I do with this project will have two speakers in it. I'll have to do some grinding to make a second speaker fit as I found that they have to be a certain size in order to maintain decent volume (about one inch diameter minimum). Question: Currently my project uses the same speaker for the FRS and the sound effects, but different power sources. Will this still eventually fry one of the two amps? If I were to trace through this small toy sound effects circuit board and jump the sound right where it comes off the POB chip, before it gets to the amplification transistor, would this do anything for me? Of course this could not be done for the FRS radio. If you'd like to see what my project is, take a look at these photos. This thing works quite well with a custom made internal antenna, but the only issue hanging me up is this sound effects mess. I have been on this for a year, and have about $1,000 sunk in the research. Needles to say I have a bunch of expensive and useless garbage sitting here. Thank you, Bruce

Audioguru, I don't have room for two speakers. I tried to insert a few different values of resistor in the + side of both circuit's speaker lines. I even used a variable resistor pot on each and played with them for some type of result. Neither will share one speaker, no mater what resistor I use. I have very little room, and do not know why I need a power amplifier when the volume is fine as is. The FRS has within it a variable resistor volme pot as it is, so I am just doubling the resistance for it's output by adding yet another one, and quite frankly it needs all the volume it can muster. The other circuit will give me sound at about 10 ohms to probably 100. 1k and 100k - nothing (that is without the other circuit wired in - that is stand alone). These two circuits will apparentley not allow my to share a speaker when hooked top one power supply - so I have went back to my original configuration where one circuit uses 3 AAA's and the other uses what it needs in way of Lithium coin cells. They share a speaker, with no resistors between, but they have their own power supplies also. This works very well, and I will leave it as it is. If it ain't broke don't fix it as I like to say. I only hoped to save a little room inside the device I made. I am going to make a second one like this, and I guess I will have to - once again, use two power supplies. Thanks, Bruce

I am going to try the two resistors tonight. I found one web page that specified 10k ohms, but did state that this may knock down some of the high end off the sound. If this is no good, then I guess I will try a lower value reistor. As for the low power IC amps. I do not need an amplifier. The volume level is good enough as it is. On top of that, I had experimented with these amps months back, had spent a considerable amount of money and time, and in each case they did not work. I do not have room for them in any case. Both of these devices are already amplified on board, though the sound effects circuit board uses a simple transistor as an amp which is not very powerful. I am told that doubling up on amplifiers does not usually work, and from experience, that seems to be correct. Thanks, Bruce

Are you saying that I need only to put a transistor at the connection of one of the two circuits at the speaker? I don't need any amplification, and the two circuits only share a common battery and speaker. If so, what should I use as a transistor 10k ohm? Since the FRS already has a volume pot, I guess I would put the transistor on the sound effects circuit to the speaker - right? Bruce