Well, I underestimated the price differential of the 15 and 65V parts kits. The good news is that I overestimated the 15V parts kit cost.
15V parts kit WITHOUT BOARD is $20. Includes all parts needed and 2" heat sinks, screw terminals. Does not include mounting hardware for TO-220s or standoffs. Includes 1500 uF 35V input caps, 470 uF 25V output caps.
65V nominal adjustable parts kit WITHOUT BOARD $30. As above, with 100 V caps and trimpots. Input caps are 470 uf, output 100 uf.
I've updated the order page. Those who have already ordered boards and want to add parts kits need not add extra shipping if less than 4 psu kits are ordered.
I'll add an incremental shipping button for those US buyers who are going up to a flat rate box later on.
15V parts kit WITHOUT BOARD is $20. Includes all parts needed and 2" heat sinks, screw terminals. Does not include mounting hardware for TO-220s or standoffs. Includes 1500 uF 35V input caps, 470 uF 25V output caps.
65V nominal adjustable parts kit WITHOUT BOARD $30. As above, with 100 V caps and trimpots. Input caps are 470 uf, output 100 uf.
I've updated the order page. Those who have already ordered boards and want to add parts kits need not add extra shipping if less than 4 psu kits are ordered.
I'll add an incremental shipping button for those US buyers who are going up to a flat rate box later on.
3 days to go and 31 people who asked for boards on the WIKI have not ordered. I have more than enough board orders to make a group buy work.
Not many PSU parts kits have been ordered. If you want the parts kit, this is the time to order. If there are not enough parts kit orders to do it economically I will refund your money promptly after a decision is made to cancel the parts kit portion of the buy.
Not many PSU parts kits have been ordered. If you want the parts kit, this is the time to order. If there are not enough parts kit orders to do it economically I will refund your money promptly after a decision is made to cancel the parts kit portion of the buy.
With the 2" heat sinks that I will include in the kit, you can get rid of about 5W in 35C ambient (inside a warm case) and keep the output junctions under 100C (see the spreadsheet on my website)
50 VAC will give you ~69VAC unregulated. Assuming that you want your regulated rails at 60V you can provide 500 mA before reaching the thermal limit. You are also limited by the diodes to 500 mA, but that's more than enough for the Leach front end. IIRC it draws around 40 mA.
==> Your transformer would be fine, but overkill.
50 VAC will give you ~69VAC unregulated. Assuming that you want your regulated rails at 60V you can provide 500 mA before reaching the thermal limit. You are also limited by the diodes to 500 mA, but that's more than enough for the Leach front end. IIRC it draws around 40 mA.
==> Your transformer would be fine, but overkill.
Hi Bob & Fred,
I don't know where ~69Vac comes from.
50Vac + 6% mains tolerance, +12% transformer regulation gives a max of ~59Vac in normal operation.
This leads to a maximum of 83Vdc after rectification. That will drop considerably when maximum current is drawn.
But, 200mA and 80V gives 4W of dissipation for 20V drop across the regulator.
Keep the regulator cool and it will be OK.
I don't know where ~69Vac comes from.
50Vac + 6% mains tolerance, +12% transformer regulation gives a max of ~59Vac in normal operation.
This leads to a maximum of 83Vdc after rectification. That will drop considerably when maximum current is drawn.
But, 200mA and 80V gives 4W of dissipation for 20V drop across the regulator.
Keep the regulator cool and it will be OK.
Points well taken Andrew. Plan for worst case. I assumed (we all know what that means) that the 50VAC was measured output on a typical day. My usual mode is to buy surplus transformers so I think measured rather than rated.
On this side of the pond, from less than careful observation, line voltage holds within 2 volts of rated - usually on the low side. My two inner city offices typically see 118V - lots of noise and some brownouts in summer but I haven't noticed higher than rated voltage.
I've had much smaller sinks on my A75 regulators that have served well for years dropping 20V at 100 mA. I don't think a Leach front end is going to draw much more than 50 mA.
On this side of the pond, from less than careful observation, line voltage holds within 2 volts of rated - usually on the low side. My two inner city offices typically see 118V - lots of noise and some brownouts in summer but I haven't noticed higher than rated voltage.
I've had much smaller sinks on my A75 regulators that have served well for years dropping 20V at 100 mA. I don't think a Leach front end is going to draw much more than 50 mA.
I've got enough take home work that I won't be able to order anything until Monday. So, I'll leave the buy open until Sunday.
Hey all you latecomers...
I'll order some extras of everything, but don't count on too many. The last buy was two years ago, and it will probably be as long before I do it again, if at all.
Hey all you latecomers...
I'll order some extras of everything, but don't count on too many. The last buy was two years ago, and it will probably be as long before I do it again, if at all.
Stupid question ...
If I cut a PSU board in half, build the two supplies as independent 15v supplies. Can I use the -15V as a positive supply by reversing my circuit connection to it ?
Basically I need two positive supplies in two separate projects, why waste a negative supply if I can use it as a positive elsewhere.
Does this make any sense ?
Thanks,
Argo.
If I cut a PSU board in half, build the two supplies as independent 15v supplies. Can I use the -15V as a positive supply by reversing my circuit connection to it ?
Basically I need two positive supplies in two separate projects, why waste a negative supply if I can use it as a positive elsewhere.
Does this make any sense ?
Thanks,
Argo.
Status
I have the boards and most of the kit parts. The 2" heat sinks are back ordered, Mouser says 3 week delivery, and has for 4 weeks. Since most of the 15V applications can easily get by with smaller sinks, is there any objection to a substitution?
For those that have ordered just boards, I will start packing and shipping this weekend.
I have the boards and most of the kit parts. The 2" heat sinks are back ordered, Mouser says 3 week delivery, and has for 4 weeks. Since most of the 15V applications can easily get by with smaller sinks, is there any objection to a substitution?
For those that have ordered just boards, I will start packing and shipping this weekend.
- Status
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