Bruce

On Fri, Feb 11, 2022 at 10:06 AM Ken KM4NFQ <km4nfq@...> wrote:

Hello Jim WA7DUY,

I guess I was lucky to find the relays in stock.
I have ordered from Newark before, although it was many years ago.
You just have to go with the distributor that carries the part.
I suggest that you order as many parts from one distributor as you can
to save on S&H.

Regards,
Ken, KM4NFQ "Not Fully Qualified"
/g/w8bhMorseTutor

On Fri, Feb 11, 2022 at 2:23 AM Jim Pruitt <jpruitt67@...> wrote:
>
> Hello Ken.
>
> I bought the Coto relay from Mouser because they showed no stock on the Sil05-1A7271L and the Sil05-1A7271D relays.? Both Mouser and Digikey list the NA05WK 5v DPTD relay as obsolete and no longer available but their searches gave no alternatives.
>
> I have no objection to using a 560 ohm resistor instead of the 540 ohm called out in the parts list.? I thought 540 was an odd value anyway but thought it might be a standard 1% value but apparently not.? My guess is that the 540 ohm value is the mathematical calculation to get the desired 3.3v out of the LM317LZ with the 330 ohm that they used in the divider and just verified that with the LM317 calculator at:
>
> If 560 is substituted for R2 instead of 540 then R1 comes out at 340 ohms (another non standard value). With R1 at 330 ohms and R2 at 560 ohms then LM317 should deliver 3.7v.
>
> Any suggestions on the DPDT 5v relay substitute of the Fujitsu NA05WK is not available and is in fact obsolete?? I do see that Newark has some of the Sil05-7271L single inline relays in stock.
>
> Thank you.
>
> Jim Pruitt
> WA7DUY
>
>
> On 2/10/2022 7:11 PM, Ken KM4NFQ wrote:
>
> Hello Jim WA7DUY,
>
> Some parts were difficult for ME to find.
> I do not know if any of these parts are still in stock at Mouser Electronics?
> The datasheets should still be available for substitution purposes.
>
> Reed Relay
> Mouser P/N: 876-SIL05-1A7271L
>
> Takamisawa NA5W-K Relay
> Mouser P/N: 817-NA-5W-K
>
> 1000pF Capacitor
> Mouser P/N: 80-PFR5102F100J11L4B
> (Check the spacing of the capacitor leads against the PCB holes before
> ordering.)
>
> 1000pF Capacitor
> Mouser P/N: 75-KP1830210631
> (Check the spacing of the capacitor leads against the PCB holes before
> ordering.)
>
> Crystal 8MHz
> Mouser P/N: 559-FC4STCBMF80B2
>
> LM317 Linear Voltage Regulator
> Mouser P/N: 595-LM317LCLPRE3
>
> LM311N Voltage Comparator
> Mouser P/N: 926-LM311N/NOPB
>
> BAT42 Scottky Diode
> Mouser P/N: 511-BAT42
>
> As Bruce suggested, I used a 560 Ohm resistor in place of the 540 Ohm resistor.
>
> Hopefully helpful.
>
> Regards,
> Ken, KM4NFQ "Not Fully Qualified"
> /g/w8bhMorseTutor
>
>
> On Thu, Feb 10, 2022 at 5:19 PM Jim Pruitt <jpruitt67@...> wrote:
>
> Hello Ken (KN4NFQ) and Bruce (W8BH).
>
> I was able to find the schematic and parts list on CoreWeaver's github page.? Thank you.? Now I have a few other questions for you and Bruce and anyone else that built it.
>
> Where did you find the 540 ohm resistor CoreWeaver used to set the LM317LZ output voltage?? I can not find that value as a standard value for 5% or 1% resistors.? Only Digikey listed a single 540 ohm ? watt 1% resistor and no stock and required 1000 minimum order and 90 cents per resistor at that quantity!? Should it actually be the standard 560 ohms?? I also question why he used an LM317LZ instead of one of the 3.3 volt LDO regulators. Does anyone know?? I assume (yes I know what they say about that) that it was because that was what he had in his junkbox but that is only a guess.? Did anyone happen to use one of the TO92 footprint 3.3v ldo's there instead of the LM317?
>
> Also I did not find any SIL 7271-L 5 volt reed relays but bought a Coto 2101 with diode.? The footprint is the same but the datasheet does not help me with orientation.? The relay is symmetrical? and datasheet does not indicate polarity but with a diode across it I would think it would have to follow the correct voltage polarity.? What did others use?
>
> Thank you.
>
> Jim Pruitt
> WA7DUY
>
>
>
>