Tom,
Somewhat related
I imagine that one could combine the universal buffer you have in conjunction with the OPA1622 EVM and add a headphone level output as an addition to a preamp based on the buffer?
If so, should a DPDT switch be used to direct whether headphones are used or the preamp out is used?
Somewhat related
I imagine that one could combine the universal buffer you have in conjunction with the OPA1622 EVM and add a headphone level output as an addition to a preamp based on the buffer?
If so, should a DPDT switch be used to direct whether headphones are used or the preamp out is used?
Yep. You could certainly do that. In that case, you could use the differential out of the Buffer to drive the OPA1622 EVM (which has differential input). The input impedance of the EVM is 1 kΩ, so I would add a switch if you plan to have the same Buffer connected both to a preamp output and to the EVM.
Tom
Tom
Thanks Tom
Something that I am curious and I am sure others are as well is the output current capability of the OPA1622. I look at an LME49600 and it is rated for 250ma. Looks reasonable to my old fashioned eyes. Then I look at that eensy teeny tiny OPA1622 and I see 100ma. Huh....It might be true but it's hard to believe.
Maybe you are able to provide some more insight into how that is. I need to see the light.
Something that I am curious and I am sure others are as well is the output current capability of the OPA1622. I look at an LME49600 and it is rated for 250ma. Looks reasonable to my old fashioned eyes. Then I look at that eensy teeny tiny OPA1622 and I see 100ma. Huh....It might be true but it's hard to believe.
Maybe you are able to provide some more insight into how that is. I need to see the light.
Tom
I'm curious to know why you mention connecting the UB to the EVM rather than your HP22 board.
Colin
I'm curious to know why you mention connecting the UB to the EVM rather than your HP22 board.
Colin
Tom did not mention this. I did. I purchased a Universal Buffer board that was to be the basis of my preamp. When I saw how the HP22 board connects to the OPA1622EVM module, I then posed the question of adding a headphone output to my preamp based on the UB.
So again, this is not what Tom is recommending but I saw it as something that could be an option on the UB.
So again, this is not what Tom is recommending but I saw it as something that could be an option on the UB.
I received it in Bangkok 14 days after Tom sent it out.
I guess it shouldn't take too much longer to anywhere else in the world.
I guess it shouldn't take too much longer to anywhere else in the world.
That's impressive. Most regular airmail shipments seem to take about a month these days.
If you want it on time, go with FedEx or UPS. I offer rather incredible rates on those.
Tom
If you want it on time, go with FedEx or UPS. I offer rather incredible rates on those.
Tom
In the moment I am looking for all the other little parts for this little amp. One of those items is an on-off switch. That is more difficult to find than I anticipated. And I made already one mistake. I saw what I thought was a suitable switch, this one: 107-SF17020F-32-21RL from Alpha (Taiwan).
But if possible I wanted one with integrated LED. Surprisingly I found one at a local supplier in Bangkok and it was delivered the next day.
In principle the switch is fine, except that is takes a lot of force to push it. Now I understand the meaning of foot-switch.
So as a warning for everybody out there who wants to buy a little switch: Look at the details and when it's called foot-switch then don't buy it. Because this is not easy to press with the hand. And at least I don't want to hold my amp enclosure with an iron grip so that I can switch it on or off.
Maybe this is common knowledge for some of you. It was definitely new for me.
Now I will probably buy this switch: 8261LHZGE1 from C&K. But I will doublecheck the datasheet if this is really suitable.
But if possible I wanted one with integrated LED. Surprisingly I found one at a local supplier in Bangkok and it was delivered the next day.
In principle the switch is fine, except that is takes a lot of force to push it. Now I understand the meaning of foot-switch.
So as a warning for everybody out there who wants to buy a little switch: Look at the details and when it's called foot-switch then don't buy it. Because this is not easy to press with the hand. And at least I don't want to hold my amp enclosure with an iron grip so that I can switch it on or off.
Maybe this is common knowledge for some of you. It was definitely new for me.
Now I will probably buy this switch: 8261LHZGE1 from C&K. But I will doublecheck the datasheet if this is really suitable.
Well, I for one find it very time consuming when searching for parts sometimes (especially chassis related) and have certainly bought parts that do not work or fit properly in their intended places. But I suppose that's part of the fun as well, discovering what works 🙂
Good to know about the foot switch as I've been eyeing them in a few occasions as well.
I generally find the data sheets to be pretty accurate these days. That said, there is the occasional surprise. For example E-Switch's PV6 series is specified to fit in a 10 mm panel ... and used to do that. But now they're just half a thread too short. What gives?!
I usually buy a couple of parts to verify the dimensions before committing to a larger order.
There are toggle switches that have the LED integrated into the actuator. That would be kinda cool. NKK P/N: M2112TCW01 (Mouser: 633-M2112C). They're not cheap, but not outrageously expensive either.
Tom
I usually buy a couple of parts to verify the dimensions before committing to a larger order.
There are toggle switches that have the LED integrated into the actuator. That would be kinda cool. NKK P/N: M2112TCW01 (Mouser: 633-M2112C). They're not cheap, but not outrageously expensive either.
Tom
It seems the switches you mention are all SPDT (Single Pole Double Throw).
I guess for the HP-22 with +/- supply voltage we need DPDT.
I just looked at the list and the least expensive DPDT (at least on my local Mouser site) is this one: M2122TCW01
Oh, that's true. You do need a double-pole switch. My bad.
Some of the anti-vandal switches are DPDT and offer LED indication.
Tom
Some of the anti-vandal switches are DPDT and offer LED indication.
Tom
Hi Tom, I have received the board and the power supply and I am going to order components from mouser soon. May I ask what specification do I need to be looking at for iec socket? I know it is not wise to solder the iec socket to the wires connecting to the board, so I research and found some cables which have crimp terminal, is there any requirements for these cables and can they be bought on mouser?
Why is it not wise to solder the connections to the IEC socket? I would prefer that over a crimp terminal - especially as few have good crimp tools. Just cover the connections in heat shrink when you're done.
I like the Bulgin P/N: PF0001/28. Mouser has them.
Tom
I like the Bulgin P/N: PF0001/28. Mouser has them.
Tom