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abador
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Posts posted by abador
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I plugged in my module that I got off of amazon with this chip installed. An onboard LED also flashes which goes to pin3 which should be the vcc. I am providing the circuit with the maximum 18 volts. Could the ic be bad or could I be overloading the internal overload protection somehow? I have another ic I can put in the circuit as well as everything else to make the circuit function so I can easily replace bad parts.
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I cracked the unit open and checked the voltage at the battery with the unit unplugged and then with it plugged in. Unplugged it reads under a volt but when it is plugged in the circuit reads 13 volts. I figure this means the charging circuit must be good but the battery is bad. The battery is a 12 volt battery. I am pretty certain that the battery is bad but could this cause it to keep switching on and off when the unit is plugged back in? Also I'm pretty sure it is lead-acid.
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I bought this battery backup system from a thrift store for $4.99 hoping to have something that I can use to power some important items when the power goes out. once I got it home I charged the battery for more than the recommended 8 hours and the battery still does not kick in when I unplug the device. Also when I plug the system back in it starts turning on and off until I remove the load from the battery plugs. Does anyone have any idea what could be wrong with it? There is a label on the outside stating that there are no serviceable parts inside but I assume I might be able to solder and unsolder stuff to the circuit board. Also if someone can find a service manual that would be very helpful.
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Hey Hero999, I like your idea. I actually found a module that was about $10 so I decided that one might be better quality so I think I might get that one. I have all the parts in case any of the parts go bad. I'll have to research how to troubleshoot if it doesn't work but I'll tackle that if the time comes. Still would have been cool to build it from scratch but I guess it was a little too advanced for my abilities atm. I'll make sure an ic will fit a perfboard when I conquer my next project. Thanks for the input.
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I have been working on a project for a while but I have run into a roadblock. The generic perf board that I bought does not fit the ic. I have looked into etching my own pcb as well as designing my own and sending it to a manufacturer to etch it for me which I found to be way too expensive for my simple circuit. Are there any places that sell mass produced boards that would fit my specific ic and be under $10 to buy? The chip would be the TDA7297.
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I attached a schematic. I have looked at other schematics for amplifiers and it has shown the volume being ether on the input or on the main power input. Since the chip has two input pins I don't know how well it would work. I could put the pot in the main power input but my pot is only rated for about half a watt. I didn't see the volume in the schematic. Also I am in the process of trying to print my own circuit board but the pins are a little weird so who knows if I will get that to work out or not. I'm using a program called freepcb.
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Where would I put the volume pot?
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Not enough details.
Is the IC too big or is it too small to fit on the pcb?
What is the IC? Is it an audio amplifier with two rows of terminals?
It is too small. It is a TDA7297 chip. I'm trying to fit it into a general pcb that would probably fit into a bread board. It doed have two rows. it stands upright as apposed to laying against on the board. -
I have an integrated circuit that doesn't fit in my pcb board that I bought. Will I break the IC if I bend the terminals? What are my options? Do I need to scrap the entire board since it won't accommodate my project?
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I have a question about a schematic for the TDA7297 chip. In the schematic it shows a place in the upper right corner labled VCC and in the left corner it is labeled as VS. I have tried to research this and someone said that VSS tends to stand for a negative charge in the schematic but that wouldn't make sense in this case because it connects to ground and the capacitor shows the side away from ground to be positive. Can anyone tell me what this means? Also I am using an audio jack for the input, does any one know how to wire the circuit for this use?
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Also I just looked at the amp on newark and the page with the item says they charge a $20 freight charge per order. Is that something I would have to pay or is it some kind of complicated thing that I don't understand?
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In your other thread the TDA7297 bridged stereo amplifier IC was recommended. Did you see its datasheet? Newark has them in stock.
A lowpass filter does not boost the bass, instead it cuts the highs. A bass boost circuit is half of a simple bass-treble tone controls circuit.
Adding a subwoofer needs a third amplifier for it, a highpass filter for both stereo channels and a lowpass filter for the input to the sub-woofer amplifier.
I got my old account back so this is abador08. I'm not going to use abador08 anymore and am going to keep this as my primary account. I looked up the data sheet but it's a little difficult for me to figure out the schematic. I think the box in the middle must be the ic because the pins are listed on the outside of it. Is the circuit inside of the box the circuitry inside the ic ir is that part of what needs to be put together? I guess the reason for me asking about the ics again is just to get ideas of more ics that might work so I can have more of a variety to pick from. -
I want to put a light in my closet which is very dark. My biggest question at this time is where would I connect this circuit to mains power? I have an outlet right by the area that I would like to put the circuit so could I just attach the wires to the contacts on the outlet or would I need to put all the wires to a box? Another question is how to get the wires to the places they should go. I don't really want to tear up my entire room just to get this light put in. Thanks for any input and have a great day.
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I'm trying to get a power supply working that I recently have built but have been having constant trouble with it. The most recent problem is that the 3300 uF capacitor discharges instantly as soon as I unplug it from the wall, despite the fact that there is a 1K Ohm resistor and LED in parallel with it and the output reading is currently very low. I have seen the LED slowly get dimmer in the past. I took a resistance reading across the output when the circuit was not energized and it was about 8K and kept rising, I thought it was because the capacitor was charging but after several attempts to discharge it the resistance was still high (17K last I saw.) I have a 5K potentiometer and a 10K resistor in series with the output. I took a reading across the DC rail as well which had high resistance. This thing has me completely stumped.
Also I have been trying to make it a variable power supply and someone said I need to use the potentiometer to control the voltage via a voltage regulator, is there any way to do this with a transistor? -
As far as jumper wire go, I have had very good experience using telephone wire, just make sure that is is not stranded wire. When using the wire as jumpers the wire goes a long way and is not very expensive. There are several wires in there and you don't need much wire. I was able to pick up about 4 feet of the stuff from Home Depot for just over one dollar.
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Thanks for all the replies everyone. I ended up putting the potentiometer in the DC part of the circuit and in series with the load. I still don't know why the readings I kept getting were so unpredictable, all I can think of is that maybe it's the fact that my multimeter only cost me $12. I put a 4.7K resistor in series with the potentiometer to bring the voltage to a more workable level but I will probably increase that to a 10K. I was able to charge a battery up to a certain point but then found out it was bad after the voltage kept dropping fast when a lead was removed. I kept trying to measure the voltage across the output and was surprised that the potentiometer was not changing the voltage at all, then I remembered that the voltage will always measure the the total across an open and put a 10K resistor across the output to get a better reading. I am now getting a stable output. Thanks for all the input.
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I probably should have labeled the out terminals in the schematic instead of labeling the resistor as load. Basically I'm just trying to use the LED as an indicator that it is working right/is on. The "load" is actually just supposed to simulate a load that could have been used on the output. I think that made it a little more confusing.
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I actually have a rectifier that is in one unit so I guess I drew the rectifier wrong, sorry about that. I ended up removing the potentiometer from the AC part of the circuit and put it in the DC in series with the output. I have still had trouble with the power supply though. I changed out the Capacitor to a 3300 uf just because that was the only other high capacitance cap that was within the voltage range. (more capacitance than I really need) I then checked the resistance on ether side of the DC circuit (+ and -) to check for shorts and the resistance was pretty high so I doubt that is the problem. I even checked the potentiometer which came out clean. I get a voltage reading every so often where it is supposed to be but this part is unpredictable and when ever I hooked it up to a 6V battery to charge, it would go back down to less than 1 volt. I am hoping if something is bad that it is anything other than the transformer just because it is so rare to find a working transformer when salvaging them. Could it maybe the 1K resistor and LED?
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Ok, I got it. Sorry it's a little messy. I tried cleaning it up but the simulation software I was using wouldn't let me take off some labels, the blued box at the bottom was only a command for the program. Basically the fuse is on one side of the circuit and the potentiometer is on the other side. The load obviously is not part of the power supply. I hope this helps give a better view of it.
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I'll see what I can do about the schematic, I'll have to draw it up. Could you please explain the impedance of the potentiometer a little bit? I know about the impedance from a coil of wire but never from a potentiometer.
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I finally finished a power supply last night after finally finding a working step down transformer. I put the 5K audio DC potentiometer in one of the AC legs from the transformer (series) and was amazed to find that I could get anywhere from about 18.6V to 3.6V. More recently I tried to charge a battery with the rectified and filtered DC output but I couldn't seem to get it above 3V and it was jumping around a lot. Could this unpredictable nature be because I have the potentiometer outside of the DC output? Could the AC ruin the DC potentiometer? I also have the fuse on the other leg of the transformer, would this protect from over current in the load that the power supply is connected to?
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I'm not sure if something like this would work. If you put a positive and negative pole in water it will produce hydrogen. Maybe if you have them close together on a rod of some kind then touch it to the fish (without scaring it away) maybe it would work. Maybe a higher voltage could work better as well but water and electricity don't mix very well if you know what I mean. I have heard of people fishing with dynamite but this is illegal in many areas and you need a special license just to get the stuff plus it's very dangerous. :P What ever you do, make sure to check your local laws and stay safe!
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ok thanks for all the input, it was very helpful.
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Thanks everyone for the input. I guess I will need a different transformer for what I am trying to do. Until I find one that will work batteries are always a good substitute for a DC power power supply, but it is also nice to not have to replace them.
tda7297 pulsing output
in Electronic Projects Design/Ideas
Posted
This is the link; http://www.amazon.com/gp/product/B00K67WI9I/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1
It was a cheep one from china so I wouldn't be surprised if there was something wrong with it. The pulsation is in the form of a buzz in the speakers, it won't play music. The speakers are 8 ohms. I did not notice the heat sink getting hot and I did have it plugged in for several minutes. The pulses are the same volume despite where I had the volume knob. The output amperes of the power supply is 1 amp so I guess I made a mistake when calculating the requirements when I bought it, I thought I actually had some power to spare but I didn't think about how it would be providing the same amount of power to both speakers. I do have a 12 volt power supply rated for 5 amps so I don't ruin the one that I bought. Will 5 amps be enough?