MC34071

[Anonymous_]

Hi,

I'm trying to build a similiar power supply to the one which can be found on the following picture:

While doing so I am having a hard time finding a non SMD MC34071 chips, that are needed, in any well known european electronic stores.

I would very much appriciate if someone could give me a decent european site to buy this chip from or if someone could tell me what a good alternative to replace this chip with would be.

 

[(*steve*)]

If all you can find is an SMD version of this chip, solder it to an adapter board, solder 8 pins into the adapter board and then use it just like a DIL chip.

I use a method similar to this when I'm breadboarding with things that only come in SMD packages.

 

[Alec_t]

Here's a DIP one which might suit, but the max supply voltage (40V) would be rather marginal.

 

[Audioguru]

The power supply is similar to the one that I fixed and I used MC34071 opamps. The TLE2141 opamp designed by Texas Instruments works the same as a MC34071 and is still made in a through holes package.

The NJM5532 will not work in that circuit because its common mode input voltage range does not go anywhere near 0V.

 

[Anonymous_]

Thanks for the responses.
I am aware of the adapter board method that you mentioned, but to be honest I'd rather keep that as my last resort and not have any SMD elements on the circuit, thank you tho.

As it goes for the TLE2141 I might aswell go for that, as that is something I was able to find. So @Audioguru thanks for that.

What I also just found is the MC34072PG chip I could get in case that is any similar to the one I'm looking for, I would love some clarification on that.

 

[Audioguru]

Why don't you look at the datasheet for the MC34071 and MC34072? The MC34072 has two opamps in it and if both are used in that circuit then the IC will get very hot and might be damaged.

 

[Arouse1973]

Amazon have some. If you need some.

https://www.amazon.co.uk/10PCS-MC34071PG-SUPPLY-4-5MHZ-MC34071-x/dp/B019R4SL82

Looks like the part is obsolete also
Adam

 

[TedA]

The MC34071/2/4 family appear to be upgraded LM358/324 sort of op-amps. Distributors list the MC34071 single op-amp as obsolete for all package types. So get your SMT units soon! See: http://www.onsemi.com/pub/Collateral/MC34071-D.PDF


The dual and quad versions (MC34072/4) appear to still be currently active product, stocked in the DIP packages. You could use three of the MC34072 duals, and just connect one of the two op-amps in each. You will have to account for the different pinout of the dual device.


Three of your requirements work against finding a substitute device. One is the high Vcc rating required. Another is the single device per package. Dual and quad devices are more popular. And SMT parts are crowding-out ones in the larger DIP package.


At first glance it might seem that a single MC34074 quad unit would work in place of all three of the single op amps, but it seems that each of the three in this circuit has different power connections, so that won't do.


I hope it is not out of place to suggest that you look for a different design. This one may "work", but can't be called a good design. There are far too many parts for what it appears to do. I wonder where you found this, and what claims are made for it. Was there a particular reason to choose this one?


It's already been pointed out that the absolute maximum supply voltage rating for the MC34071 is marginal for this circuit. This is just one of many foolish things to be seen in the schematic.


Ted

 

[Audioguru]

The MC34071/2/4 family appear to be upgraded LM358/324 sort of op-amps. Distributors list the MC34071 single op-amp as obsolete for all package types. So get your SMT units soon! See: http://www.onsemi.com/pub/Collateral/MC34071-D.PDF end.

No. The MC3407x is better than the MC3317x but the MC3317x is an improved LM358/LM324.
No again. ON Semi say the MC34071 is in production but its old through-holes case is obsolete. Digikey has thousands in stock with the surface-mount package.

The dual and quad versions (MC34072/4) appear to still be currently active product, stocked in the DIP packages. You could use three of the MC34072 duals, and just connect one of the two op-amps in each. You will have to account for the different pinout of the dual device.

Using only one of the opamps is fine.

Three of your requirements work against finding a substitute device. One is the high Vcc rating required. Another is the single device per package. Dual and quad devices are more popular. And SMT parts are crowding-out ones in the larger DIP package.

Thousands of this project have used the TLE2141 that has many of the same spec's as the MC34071 which is why I selected both of them.

At first glance it might seem that a single MC34074 quad unit would work in place of all three of the single op amps, but it seems that each of the three in this circuit has different power connections, so that won't do.

Also it will overheat.

I hope it is not out of place to suggest that you look for a different design. This one may "work", but can't be called a good design. There are far too many parts for what it appears to do. I wonder where you found this, and what claims are made for it. Was there a particular reason to choose this one?

It is a cheap Chinese kit that is mostly a copy of a Greek kit that is a project for about 15 years at www.electronics-lab.com that had many overloaded parts. I fixed it. The improved circuit works very well but the cheap Chinese copy does not and is being sold as clearance and is replaced by a similar but better kit.

It's already been pointed out that the absolute maximum supply voltage rating for the MC34071 is marginal for this circuit. This is just one of many foolish things to be seen in the schematic.

If the 28VAC transformer idles at 29.5VAC then its DC is +40.3V plus the -1.3V= 41.6V. its maximum is 44V. The original Greek kit and the Chinese copy use TL081 opamps that have a maximum supply of 36V and also need a -5.6V supply. Very few if any opamps have a maximum supply that is higher than 44V.