Made a mic

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ThanX for the Advice Guys..... I think I will try a Few Different Pre-amp Designs as I just got a Bunch of Op-Amps and other electronix for free....

The way I got the Op-Amps for free is I went on this Site that sells electronix to Large Companies and I said I owned a Small Elecrtonix company and wanted samples of different Op-amps and other electronix like Transistors and Voltage referance and Diodes and they let me Pick out a Bunch of Different Op-amps ect and they are sending them to me Via Fed EX for FREE!!
They also said that if I ever need any samples of any electronix components that they will send them to me for Free.....

So the only thing I have to Pay for in my Pre-amp project is the Caps and Resistors and the PCB Board which greatly reduces the Cost.....

If you guys happen to know of any other fairly simple Pre-amp Projects (With a Parts List and PCB Design) Please let me Know....

ThanX
 
Minion said:
ThanX for the Advice Guys..... I think I will try a Few Different Pre-amp Designs as I just got a Bunch of Op-Amps and other electronix for free....

The way I got the Op-Amps for free is I went on this Site that sells electronix to Large Companies and I said I owned a Small Elecrtonix company and wanted samples of different Op-amps and other electronix like Transistors and Voltage referance and Diodes and they let me Pick out a Bunch of Different Op-amps ect and they are sending them to me Via Fed EX for FREE!!
They also said that if I ever need any samples of any electronix components that they will send them to me for Free.....

So the only thing I have to Pay for in my Pre-amp project is the Caps and Resistors and the PCB Board which greatly reduces the Cost.....

If you guys happen to know of any other fairly simple Pre-amp Projects (With a Parts List and PCB Design) Please let me Know....

ThanX
Click to expand...

Cheater!!!!! :eek:

What company is it!?
 
This is the Place that gave me the Free samples...

http://www.ti.com/


I just had to Register on there Site with your Company Name (my made up company is called "Alcor Electronics") and then Confirm the Registration and then I just Looked up some of the Stuff they sell and then clicked on the "Samples" Link and they let you select up to 12 of each Product and up to 8 Different products in a Sample Delivery....

I got them to send me 8 "TL074" Op-Amps and 8 "LM4040 Voltage Referance" and 4 "LM6134 Op-Amps" ...I tried to also order some "2N3904 Transistors" but they didn"t have them which is OK cuz I can get them on e-bay for $5 for 100 of them.....

I believe they let you order up to 8 different Samples per week....
I only Ordered mine yesterday but allready got an e-mail today saying that they have been sent out....I think I am going to try to Milk these Free samples for all it is worth as it sure beats paying $10+ for Shipping an Item that only costs $1 or $2.....

Cheers
 
Minion said:
This is the Place that gave me the Free samples...

http://www.ti.com/


I just had to Register on there Site with your Company Name (my made up company is called "Alcor Electronics") and then Confirm the Registration and then I just Looked up some of the Stuff they sell and then clicked on the "Samples" Link and they let you select up to 12 of each Product and up to 8 Different products in a Sample Delivery....

I got them to send me 8 "TL074" Op-Amps and 8 "LM4040 Voltage Referance" and 4 "LM6134 Op-Amps" ...I tried to also order some "2N3904 Transistors" but they didn"t have them which is OK cuz I can get them on e-bay for $5 for 100 of them.....

I believe they let you order up to 8 different Samples per week....
I only Ordered mine yesterday but allready got an e-mail today saying that they have been sent out....I think I am going to try to Milk these Free samples for all it is worth as it sure beats paying $10+ for Shipping an Item that only costs $1 or $2.....

Cheers
Click to expand...

Think I'm gonna have a go at it too!
Can't beat free opamps!!!! :rolleyes:
 
;) Guess What ??? My Free Sample Op-Amps showed up!!!! Allready!!

I only ordered the samples on Saturday and they showed up today, so that is some Pretty damn good service for free samples....

I got 12 Op-amps delivered today ,8 of the TL074 and 4 of the LM6134 and they are going to send me some voltage referances when they come in stock...

So here is the Problem that I hope you guys can help me with...

I didn"t realize that these Op-amps were so small!! I mean they are less than 1 cm long and 1/4 cm wide and they have 14 pins Total on them (7 a side) which makes it "VERY" difficult for me to work with...

How do you solder pins that small on to a PCB?? Also how am I supposed to Etch such small traces on my PCB?? My PCB design is pretty small (2.5in x2.0in) but the OP-Amps are even too small for the PCB Design (They are SMT I think)....

I think I can Probably change the design so that the Op-Amp fits but what I am more worried about is Etching the PCB as the resist pen I have will not draw fine lines so I was wondering If I could use a regular Fine tipped pen (the resist pen was just a sharpie) ?? Like any Pen that is waterproof??

Also How do you solder them to the PCB after and If I can make one successfully ?? Do i try to drill little holes in the PCB for the Op-amp and then solder the Pins and try to remoove any solder that is shorting any other pins?? Is there some sort of Conductive glue I can use instead??

Any tips or help at all in this area would be Great!! I was all hyped on this Project up untill I was how small the Op-amps were and then I suddenly felt that I was in way over my head as it looks like you would have to be 2 inches tall to successfully solder one of these Chips....

ThanX Guys...
 
If they are that small, they are surface mount. Those are also quad opamps, not sure if that was what you wanted.

Try using the free software you can get from ExpressPCB to draw the traces, print on a transparency, expose on presensitized PCBs, and develop. You don't drill holes for surface mount, you just solder them to the pads. It's difficult, especially for me because my hands shake.

When you order opamps, be sure to get DIP versions which are thru-hole.
 
Thanx But the PCB kit I have is Not the same as those ones you posted in the Links...

The One I have you Draw or Print the PCB design onto to the Copper side of the PCB Board and then you Soak the Board in a Solution which dissolves the Copper accept for were you drew the Traces and then you soak it in a different Solution which dissolves the Ink which leaves you with a PCB Board with Copper Traces that are the same as what was drawn on the Board....

If I can"t get a Good enough PCB with my PCB Kit i"ll try the other Method that you Posted....

Cheers
 
well I don"t think I am going to have to worry about the SMT Parts because I just Picked up some OP-Amps in the Dip Package But the pins don"t line up correctly with my Schematic so I will have to Try to Find a Different Project that can use this Op-Amp.....

Do you Folks know of any Schematics that use the LM2900 Op-Amp for Makeing a Mic Pre-amp??

Cheers
 
I just ordered a Bunch more OP-amps but this Time I made sure that I got the ones with the DIP Package and also most all of the Op amps I ordered are "Burr Brown" op amps which I hear are some of the Best quality (and Highest Priced) Op amps for makeing high end Audio equipment....

I am getting about 25 Burr Brown op amps of about 6 different types (some of these Burr Brown Op-amps sell on e-bay for as much as $30 Each!!) and I also Figured that since these are More Popular op-amps and are used in High end equipment that It might be easier to Find Schematics for useing them to Build pre-amps....

These are the Ones I have ordered all are Burr Brown ..

INA217
http://www.chipdocs.com/pnsearch/download.html?partid=745394

OPA134PA
http://www.chipcatalog.com/TI/OPA134PA.htm

OPA137PA
http://www.chipcatalog.com/TI/OPA137PA.htm

OPA2107AP
http://www.chipcatalog.com/TI/OPA2107AP.htm

OPA2277P
http://www.chipcatalog.com/Datasheet/48118B69E3B89D1C07939D243CF45C46.htm

OPA602BP
http://www.chipcatalog.com/TI/OPA602BP.htm

OPA627AP
http://www.chipcatalog.com/TI/OPA627AP.htm

Some of the Models are Back ordered so I won"t get them for a while but some will be here in a couple days....

If you guys happen to know of any pre-amp projects that use any of these Op-Amps Please let me Know as I am not nearly advanced enough to Design my own though I might give it a Try.....

ThanXX
 
OPA627 is the really pricy one, it's super high performance with a price tag to match. OPA2107 is also up there.

Many of those on your list are FET input single opamps, so look for any project that uses something similar, like TL071, or often BJT-input opamps too. Most preamp projects will use dual opamps though, you're getting a few of those too, and you can sub those for 4560, 4580, TL072. Sometimes you can sub for NE5534 or NE5532 successfully, but not always, so check the design's project notes. Finally, INA217 is an instrumentation amp, which I don't know that much about, but I've seen designs for it. In fact there is a mic amp design in its datasheet.

Unfortunately I was just looking at TI's supply, and their stocks are ridiculously low. My most-used opamp, OPA2134 (dual version of 134) is out of stock until at least September :eek: :( :mad:
 
Thanx for the Tips, I have been reading up a Lot on Op-amps and I have learned quite a Bit but I am still FAR from knowing how to design something myself....

Actually many of the Op-amps I ordered are Back ordered, Out of the 7 that I listed only 3 of them were in stock and the rest won"t be in till June...

I am getting 4 of each that I listed in the DIP Format For "FREE!!" (Man I love getting Stuff for Free...LOL) .... And It seems from the TI web site I can keep ordering free samples Forever but I don"t think I will Push my luck...

I won"t order any more Freebies till all of my Backordered stuff comes in and I have a whole Bunch of Electricronix Gear comeing soon Like diodes , Transistors , Resistors ,Caps, Pots,PCB"s, Ect that i ordered off of e-bay..(Man you sure can get a Lot of Electronix Stuff for $50 if you Look hard enough)

And I figured out a way to Solder Small SMT Parts without to many problems and it is useing Solder Paste...I just put a super small Dap of Solder Paste on each Pin and on each Contact on the PCB and then Just Position the Part on to the PCB and you just Touch the Soldering Iron to the Pins for a second till the Paste heats up to about 220c and then it melts and hardens when it cools down and without much mess and without Frying the SMT Part as it"s melting point is MUCH lower than regular Solder.....

I have also found a way to etch really Fine Leads on a PCB, I basicly just use a Resist pen (Sharpie) that has a Really Fine tip.......

Now I just have to Find some schematics and Parts lists for a Project that I want to do....

If I ever run Into a Problem or need help with something is it OK for me to message you for some help?? Cuz you seem to know a lot about this Stuff and well I don"t ..lol

I probably won"t jump right into a Project right away as I will wait till my Parts show up but when they get here and I have my little workshop set up I"m sure I will Need quite a Bit of Guidance....

ThanXX
 
I read that if you request free samples more than once (or twice, can't remember) in 6 months that TI will black list you.
 
Well Luckilly i have only requested sample Twice and I will not need anymore once they all show up (Most are Back ordered) as I will have enough Op-amps to Build 30 Amps...

Actually some of my Burr Brown Op-amps showed up yesterday (Friday) and I only ordered them on Wednesday Night which is Like a 36 hour shipping service and they are sent from Singapore....

The ones that showed up yesterday were the "OPA2107, the OPA134, and the OPA137 but I can"t wait till the OPA217"s show up as I found a Very easy to follow schematic for makeing an extremely high quality Mic Pre-amp with Phantom power....

I now just need to find some cheap Transformers for building the Power supplies...

I have a Cheapo 6 Channel Line Mixer (Mono) which I might scavange for it"s Transformer and or Power supply and use the Enclosure to build my Mic Pre in or I might just make an enclosure out of Wood with a Nice Vaneer on the Outside to get that Cool Retro look.....

Do you guys know if I can find useable Transformers/Power supplies out of Old stereo recievers, Radios ect??

I would Like to use AC/DC adapters to power them but I hear that they can create a Lot of Noise but I am sure there is a way to overcome that by wireing in some resistors and Poly Caps???


ThanXX
 
Hey,"mshilarious" I wanted to know if you can answer a couple of questions for me??

I have a Really Crappy 6 Channel rack mount Line Mixer that I was thinking of Trying to Mod into a better Mixer or maybe into a 6 ch Pre-amp...
This Mixer has a Really low level sound and has a Lot of Humm....

When I opened it up yesterday I noticed a few things that concerned me..
Next to the Power Transformer there are a couple 470uF electrolytics but one of them seems to be Leaking, There is a bit of Dark Brown colored stuff that looks to be oozeing out from the Bottom of the Cap...I"m not sure but It could also be some sort of Glue cuz it is the same color as the Glue fastening the Transformer into Place and it has dried up into a Crusty layer at the bottom of the Cap which is why I"m not sure if the Cap is leaking or if it is Glue....

Could a Bad Capacitor in the Power supply cause a Humm and Make the output volume level really low??

Also I was thinking about maybe scangeing the Op-amps in it to better ones...
Each channel of the Line Mixer has 2 "Toshiba TA7120P" Pre-amp Opamps which are 7 Pin Op-amps...(I don"t know why it has 2 per channel as it is a Mono Mixer...Yea I know a pretty shitty mixer)

I searched on the Net for info on this Op-amp but I couldn"t find very much info on it..I did find a Very brief datasheet for it but it didn"t tell me the Pin configuration..The opamp is also only has a Single Row of pins unlike other op-amps which usually have 2 Rows of pins with from 4 to 7 Pins per row....

Do you happen to know what the Standard pin configuration is for this type of Op-amp??

I"m thinking if I can"t get it to sound better that I might just Gut it and use it to build my Pre-amp into and I"m sure I can also use the Power transformer for the pre-amp and it has 7 10K pots and 1 50k Pot which I can probably use for the Gain/Attenuator Knobs....

ThanXX
 
Minion said:
Next to the Power Transformer there are a couple 470uF electrolytics but one of them seems to be Leaking, There is a bit of Dark Brown colored stuff that looks to be oozeing out from the Bottom of the Cap...I"m not sure but It could also be some sort of Glue cuz it is the same color as the Glue fastening the Transformer into Place and it has dried up into a Crusty layer at the bottom of the Cap which is why I"m not sure if the Cap is leaking or if it is Glue....
Click to expand...

Sounds like it's just flux that melted when the joint(s) was soldered. Nothing to really worry about. You could clean the board of flux with special solvents or pure alcohol.
 
ThanX for the Suggestion but I don"t think it is Flux because it is on the opposite side of the Board that the Soldering is on and there is no other stuff like that anywere else on the Board and it also seems like quite a Lot of flux to be leaking out of electrical Grade Solder which is usually less than 0.6mm thick.....

ThanX anyways... :cool:
 
Minion said:
ThanX for the Suggestion but I don"t think it is Flux because it is on the opposite side of the Board that the Soldering is on and there is no other stuff like that anywere else on the Board and it also seems like quite a Lot of flux to be leaking out of electrical Grade Solder which is usually less than 0.6mm thick.....

ThanX anyways... :cool:
Click to expand...

True. You never know with that cheapo-stuff!!

Just build your own MIXER!!!!

Eventually I'm going to build a complete signla chain.

Mixer, Preamps, compressors, EQs, Tube Microphones!
 
Minion said:
Next to the Power Transformer there are a couple 470uF electrolytics but one of them seems to be Leaking, There is a bit of Dark Brown colored stuff that looks to be oozeing out from the Bottom of the Cap...I"m not sure but It could also be some sort of Glue cuz it is the same color as the Glue fastening the Transformer into Place and it has dried up into a Crusty layer at the bottom of the Cap which is why I"m not sure if the Cap is leaking or if it is Glue....

Could a Bad Capacitor in the Power supply cause a Humm and Make the output volume level really low??
Click to expand...

It's glue. Bad caps could cause hum, but probably not the low level. Replace them with better caps, like Panasonic FC or Nichicon PW, 1000uF. I would also replace the voltage regulators and heatsink them if they don't have them.


Do you happen to know what the Standard pin configuration is for this type of Op-amp??

I"m thinking if I can"t get it to sound better that I might just Gut it and use it to build my Pre-amp into and I"m sure I can also use the Power transformer for the pre-amp and it has 7 10K pots and 1 50k Pot which I can probably use for the Gain/Attenuator Knobs....

ThanXX
Click to expand...

Yeah I would gut it. I can't find much on that opamp, and more importantly I can't locate an upgrade in that package. And without a schematic it would be a pain to figure out upgrades for the rest of the circuit.

Most of the cost of a DIY project is the case, connectors, knobs, pots, and power supply, and most of the time is fabrication. All of that is done for you, all you have to do is pick a mic pre that you like (from tested designs) and drop it in the box.

Edit: one thing to check is the power supply voltage. If this was a -10dBV level mixer, it might only be +-12V or less. In that case, you will probably need to replace the transformer, the voltage regulators, and maybe some more caps in the power supply so you can get +-15 or 18.
 
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