CALAHAN

I thought this was a simple question. No-one wants to put in their 2-cents as to what to put in the middle to get two electronic devices to run off of one power supply so they don't fight each other for amperage and/or voltage? Tonight I will attempt the 10 ohm resistor on the FRS posistive to the bateries and see if that works rather then on the sound effects chip. Then perhaps the silicone diode also if the resistor test fails to meet expectations. Bruce

Hi, I am trying to run a FRS radio (3 AAA's) and a simple printed on board chip sound effects circuit board (generally 2 AA's, but will work with 3 AAA's it seems without frying it, and it gives me added volume which I needed), off of the same 3 AAA power supply. I was told to use a 10 ohm resistor in line with the power end of the sound effects PCB off the positive battery post, and I get reduced volume and distortion. I was then told to use a silicone diode, and that resulted in reduced volume, and the radio not working at all (the radio is not hooked to any of these components by the way). I also tried a Zeener glass diode, and that seems to have fried the receive end of the FRS amplifier. I have tried a few different values of resistor and I can only get low and distorted sound out of the sound effects PCB (mind you that I am over volting this thing, and it is still too quite). Does anyone know what I can use and where to put it, so both of these devices can run off of one power source? The sound effects PCB does not run continuously when the radio is powered on, but it will be used intermittently on occasion when the FRS is on. Thanks for any help. Bruce

I've had to take a break from these electronic projects for a bit for a couple of reasons. But, I did go into Radio Shack and buy one of these 741 Op Amps. There is no data on the back of the package, so I have no idea if it is even close to doing what I want. I have not pulled up the internet info on it yet either, and when I do, I'm sure there will be a completely different configuration of capacitors and resistors that will need to go with it from what is in any schematic I may find. As for my 3v toy chip amplification project, I want to try this TDA2822M to see if it works with my 3 volt power supply feeding both the amp and the circuit board (it did not work with the MC34119 which was a waste of time and money). Of course though I have to order one of these things, and this takes time, then I have to get time to pull the bread board out and all of my alligator clips - again. Once I get one of these amps down where it will work, then I can re-create more for my toy prototyping projects. I will try audioguru's schematic for splitting the 9 volt battery to feed the 3 volts for the toy chip, with the other voltage of the battery going into one of these amps. I have tried about 3-4 different amp options and none of them have worked with my project yet. The only success I have had so far is when I powered a 386 off of a 9 volt separately from the toy IC which was fed off it's own 3 v supply. This configuration takes up too much space of course, but I have not tried the 9 volt split to power both yet as time is a commodity I have little of. Perhaps this weekend I will attempt all the different configurations with fresh batteries. The second project I was working on which was amplifiying the Radio Shack chip recorder, both off of one 9 volt battery, has also been put on hold until I can get this 3v toy IC chip amp working. Is there any specifics I need to know, or a special schematic I need for this TDA2822M before I order a few of them? Bruce (CALAHAN)

Sure I could use a servo, as long as it is small. But this basic stamp processor is the issue. Can I buy one that is already made up to do what I want? I bet this would require creating some kind of circuit board, inserting a chip and programming it. This would probably be cost prohibitive, beyond my capabilities, and take up too much room in the toy. Am I right? Bruce

I'm trying to find a micro DC motor that will run at 1 rpm. Basically I need a battery powered analog 60 second stop watch that I can hack open - which I cannot find anywhere. Even a battery powered wrist watch with a sweeping second hand would do, but not one that jumps like the quartz movments do. I realize that motors this slow would require reduction gearing and that is fine, as long as the gearing is either on top of the shaft or integrated within the assembley which cannot be more then 1 inch in height. Does anyone have a connections for a product like this? This is for a toy project I am working on. Thanks, Bruce

I'll try this tonight. Teh gain I assume is adjusted by the resistor you specified, becuse I have no pot of other device to to manually make this adjustment. I also don't need much volume, just a touch. I will create this exactley as you have it here. Bruce

Here is the schematic I used. The next page of the text states "This first circuit ti the easiest. Just place a 10k resistor between your micro controller and the MC34119. If you want to drive a 8 ohm speaker watch out that you don't pull too much power from your power supply. If you do place 39 ohm resistor in series with the speaker." Notice that he wasn't really telling the truth because there is also a second 10k resistor between pins 4 and 5? In any case, I powered the breadboard with the 2 AA's, and ran both the toy chip and this thing off the bread board power, using the common ground etc... and it did nothing but sat there. I tested the chip to see if it was working, and it did by itself with the low volume sound effect that I always get (The one I want to amplify). I hooked the toy chip speaker wires (remember that I am running off of snipped speaker wires here from the toy chipboard - if it makes any difference) to the inputs marked "IO PORT" and the other to "VSS", The rest as it is shown on the schematic. I had another MC34119 schematic off someone else's page, but it had completely different resistor values on it and even some capacitors, all of the values I do not have. Needless to say the Motorola reference sheet on these things, with it's illustrations of common schematics, is just as bad as the LM386 in way of extra capacitors and everything else under the sun. I don't have room for all of this stuff. I know it can be done with just a few small components because I have seen it done in other toys. I also do not want a volume or variable resistor. I don't have room for it. There must be a fixed resistor that can go in it's place. Thanks, Bruce

Audioguru, I have to give you guys credit that you can get any of this stuff to work. I have spent loads of money, buying electronic components, resisters that are of varying values, and having to guess as to what the wattage should be as none of the schematics I have seen either for the LM386 or the Motorola amp give a resistor watt rating. I bought all of the lower ones (1/4, 1/2, 1). I tried the LM 386 with this toy chip, got it to work one night, busted the little pot, and have never been able to reproduce the clear amplified sound I had again. I never bothered to try the 9 volt split you posted on the breadboard because I can't get anything else to work - so why bother?. I then went out and spent more money on more resistors, and more capacitors because every schematic one finds on the web for these chips have different component values. I tried this Motorola MC34119 headphone amplifier which is equivalent to a NJR NJM2113 (Mouser Part # 513-NJM2113D), and I can't get this thing to make any noise! I have looked for more schematics, and out of the three I found, all three are different. After all this is said and done, I should have just went to the local college, found an electrical engineer, gave him the chip from the toy, and paid the guy to solder a few working amplifier boards together for me. The LM386 was disappointing, but this MC34119 really has me irked because it is supposed to run off a voltage as low as 2, and it doesn't do anything. I even searched and found this silly 39 ohm resistor to put in line with the output to power the 8 ohm speaker. Bruce

What do you think about this UTC KA8602 as an audio amplifier? Bruce

In reference to the distortion, is there something I can put in place of the pot that would keep the input from what I assume is overdrivng the 386? With this 3.3v splitter, can I still run the 386 off the 9v while also tapping off the 3.3v? Thanks, Bruce

Well I hooked it up, and it does seem to amplify. It is a bit distorted, but I guess I'll have to live with it. The .047 capacitor comes in both a plastic green design and the usual ceramic disc. Any difference? I bought two new pots - one 100,000 and one 10,000. Both create a bit of distortion. I tried two different speakers also - and it is the same. The issue I have is that now with all of these capacitors, I don't have room. In any case, can I get the schematics to create the 9 volt splitter to 3 volts and see how that works? Tomorrow I will buy a new Radio Shack chipcorder and see how that works on this 386 schematic you posted above. Bruce

Guru, O.K. but in this case, I was powering both off of one battery. So I just connect the battery wires from the IC to the positive and negative of the breadboard which has the 9volt battery at the other end? Bruce

Guru, I don't understand what you mean about connecting the battery negatives together and discionecting the original IC speak negative. Where does the speaker negative go then? I tried your diagram. The only thing I don't have is the .047 capacitor. Perhaps the pot is bad because I didn't get any amplification out of it above the normal volume, and as I tried to turn it, I got nothinmg but variable volumes all with distortion. This is of course for the toy chip, not the Radio Shack chipcorder because that is fried. Is there anyway of eliminating the pot? I don't really want it. And is the .047 capacitor necesary? It's just a filter isn't it? Bruce

PROJECT 1: I attempted to trace the circuit board for the toy sound effect IC, but my eyes just can’t handle it. I tried to re-create the colors of the resistors as best I could. This configuration does amplify. However, I have to use one of the pots or trimmers (whatever it is – variable resistor?) that I bought in a Radio Shack mixed bundle package. This one happens to be printed with the 10k 341 on the side. Any other setting except for wide open is distorted. Through an 8 Ohm speaker it is loud, and a touch distorted. I am unable to turn the pot down, because it distorts. When using the 16 Ohm speaker it is even louder but not distorted. This board will have to be fitted with an 8 Ohm because of size restraints. Removing the 10 uf capacitor from pins 1 and 8 is not loud enough. The other issue with this configuration is that the op amp needs 9v and the IC needs 3v. I need to power both off a 9v, or comparable sized source. PROJECT 2: this set up is basically the same as before. In this trial I kept the 10 uf capacitor in place between pins 1 and 8. The 10k trim pot was retained, but better luck was gained from a different one, which was unlabeled and has since broken. I was finally able to get amplification from the 386 with powering both devices off of one 9v. However, after some time, I could smell something melting and the IC board’s LED remained on and quit working. It must have fried. I checked for shorts but there was none. In this application I would need to figure out how to get the clearest amplified sound from the 386 (if it doesn’t burn the IC board again!). I assume that if I could figure out what the resistance the pot is creating for the best sound, I could buy an equal resistor to match it. This requires, I would suppose, reading a multi-meter – something I have not been able to figure out at this time. This project has cost me quit a bit of money at this point, and has been very discouraging, especially after I smoked the Radio Shack recorder. As can be seen, I am very new to this field, and though I understand the principles, I do not know how to wire a voltage splitter, or what types of parts/values, I need to buy. I’d be willing to pay someone to solve these issues for me by drawing up a wiring diagram. To accommodate the small amount of space I have for Project 1 - I purchased a “Simple 1 Watt Audio Amplifier” kit from a company out of Connecticut called SCI-TOYS. This utilized a MPSW45A Darlington transistor, two 100,000 ohm resistors (brown, black, yellow, gold), one 10,000 ohm resistor (brown, orange, and gold), and a 50 ohm resistor (green, black and gold). The only problem is that the company shorted me on one of the 100k resistors, and the 50k had a different variation of colored bands so I don’t know what value it is. Henceforth, I could not see if the thing worked as specified. I tried substituting the 100k resistors with a few extra 10k I had, and the volume was lower then the original sound effects. I understand that this kit is splitting the 9v power supply to feed the transistor at 4.5v. But again, this didn’t work for me, and I am running out of patience. If anyone can help, I’d appreciate it. It took me a few hours to draw this up to better explain my two projects. Thanks, Bruce

I'm sorry, I guess I shouldn't have proposed this idea here becaue this is way over my head. I don't meet the minimal knowledge for this stuff. Everything I do I have researched on the web looking for schematics and reading. I understand where you are going, but I do not know any of the values of the transisors, or resistors needed, or where to wire them up. I guess I need a schematic. I'll make a sketch of how I wired my two projects at work tonight and post it later. Perhaps one of you guys can figure out how I can pull this off while taking up the least amount of space inside the toy as possible - if it can even be done. Bruce

With the transistor idea, what kind of transistor, and what value resistors? I got the Radio Shack chip and the 386 to work off of one 9 volt, the there is no amlification anymore. Bruce

Hi, I'll look into the LM317L. Perhaps I can do a search on the net to get a wiring diagram of how to connect the capacitors and resistors. Hopefully there is room for the parts in the toy. Can I create a 9 volt split to 4.5 volts and use the split for the chip but yet patch off the ful 9 volts that passes the resistors for the split? I think the chip will run on 4.5 without frying it. Would this work? - giving me the 4.5 volts needed for the chip and the 9 for the op amp at the same time? As for powering the message recorder, (in my second project mentioned initially), and the LM386 both off of one 9 volt battery, I tried this and I only get a hum out of the speaker. What's the sercret to get it to work? Thanks, Bruce

Hi, I am new here, and I am not very experienced with electronics. In fact, I am just learning. I am not good with message boards either. I have a few pet projects I want to get through, and that is is far as I will need to go electrically. My biggest issue is this; I have removed a POC board with two sound effects from a toy, placing it in and splicing it into the power supply of another toy. The original toy worked off of two AA's, and the new one off of two AAA's (no issues there I don't think except for possibly amperage right?). The sound effect from the original toy is not quite loud enough. It works , but I need a bit of a boost in volume. I also have little room to work with. The speaker is probably 8 ohm. I have been experimenting with the 386 op amp. I created a breadboard circuit and the amplifier works with the toy IC board running through it. However, the IC board requires 3 volts, and the 386 does not seem to want to sound good on anything other then 9 volts. How can I split the 9 volt to run both of the devices at once? Again, I have little space to work with. I may not even be able to fit the op amp and it's few capacitors in the shell of the toy. I may have to look to one of those "Simple 1 watt amplifier" utilizing that odd named transistor. I tried powering the op amp off of a little thin 12 volt battery I bought that supposedly powers the key chain activated on/off car alarm systems. The op amp was not as loud as it is with the 9 volt, and the sound was a bit distorted also. Another situation I have is that I have created a sound effect by using a Radio Shack message recorder. It needs 9 volts, but again is not very loud. The Op amp needs 9 volts to run also, so how can I power both of these with the least amount of batteries? Can I use one 9 volt for both? See what Mean, I am way behind you all here on this board. Thanks for any help, Bruce